Got an old clunker of a machine that can't even surf the internet without slowdowns or crashes? Luckily, modern computers are cheap. Dirt cheap. We set a top threshold of $400 and found some computers that are pretty decent to replace an older machine.

With all budget systems, don't expect video editing, advanced photo processing, computer gaming powerhouses. Instead, all of these machines are best suited to users who like surfing the internet, typing up documents, and playing casual games. While users might be able to sneak in some light video editing, light photo processing and light gaming, anyone who considers themselves a power user expecting high performance in any of these areas should consider opting for a more expensive machine, or in the case of a gamer, going with a similarly priced game console.

HP

HP is one of America's largest computer manufacturers, and the company does a pretty good job of giving users on a budget a fair amount of bang for their buck. We're looking at the HP Pavillion Slimline s3600z series of computers. We configured a machine for about $380 which included Windows Vista Home Premium, 2GB of RAM, an AMD Athlon 64 X2 dual-core processor running at 2.3 GHz, a 250GB hard drive and included an on-board ethernet port. The system doesn't skimp on multimedia features either, with a built-in 15-in-1 card reader and a DVD burner.

What's missing? The real hole missing from our current setup would be WiFi, which is common in so many households. The system also doesn't ship with a monitor or speakers, however that omission is much more forgivable given the price point, and the fact that many computer buyers have those lying around anyway.

All-in-all, HP's system isn't too bad, and HP manages to pack this inexpensive system in an attractive slimline case which won't take up as much space as a regular desktop machine. However, with that smaller footprint, the machine loses additional internal expansion slots, if you're into that sort of thing. We figure many people don't really like opening up the machine anyway, so the loss of PCI slots isn't that big of a deal.

Dell

One of the original build-to-order manufacturers, Dell helped pioneer the low-cost PC model back in the mid-90s. Their current incarnation of low-cost machines is the Inspiron 518 line. Rather than opt for the less expensive AMD processors, Dell chose to include low-end Intel dual-core Pentium E2220 processors running at 2.4GHz inside their sub $400 machine. Don't get caught up in the megahertz myth, Pentium processors are less efficient than their Core2 counterparts, so even though the sub $400 machine runs at a similar clock speed, it's going to be much slower.

Other specs on the Inspiron 518 include a roomy 320GB hard drive, 3GB of RAM, a 16x DVD burner and integrated Intel graphics. The machine runs Vista Home Basic, which omits many key Vista features but is cheaper and less resource intensive than Home Premium.

Again, missing from this system and most of the systems on the list is a wireless network adapter. Users looking to use this system in their home might have to either go with a wired connection or spring for a wireless network adapter, which can cost about $20-$50. No monitor or speakers on this model either, though the machine does include the requisite keyboard and mouse.

ZT

We wanted to check out a non name brand machine, so we gave ZT a look. While we can't vouch for the history of their brand, the machine they created at $400 is comparable to the big names, and even excels in a few areas.

Specs wise, the ZT Element 2046Vi-33 is pretty similar to the big guns, with an Intel Pentium dual-core E2200 processor running at 2.2 GHz, 2GB of RAM, a 250GB hard drive and a DVD burner. The system's main draw is its graphics card. The computer isn't exactly better in terms of specs than all the others we've seen, but the GPU is a more adequate NVidia GeForce 7050, meaning its likely to play some games at basic levels.

The ZT runs Vista Home Premium and also has integrated ethernet. Of all the machines, the ZT has the best graphics chipset, so cheap systems purchasers looking to play Spore or other 3D games at the lowest graphics level might be able to squeeze by with this machine. Don't expect the experience to be great, but it'll eek by.

Acer

One of the workhorses of the tech scene that doesn't get much respect is Acer. The company puts out solid mid range and high end machines, but doesn't spend the marketing and design money of companies like HP or Dell. Acer's $400 Veriton VM410 (UD4201C) take some of HP's cost saving tactics like including an AMD processor, but also include some nice expandability options like 4 USB ports.

The Veriton specs out with an AMD Athlon 64 X2 4200+, 1GB of RAM, a 160GB hard drive, DVD burner and instead of going with a home operating system, the machine includes Vista Business pre-installed and an option to downgrade to Windows XP, which could save some resources on the meager RAM option.

All in all, Acer's cheapest computer isn't its strong point. We're inclined to go with other options, since this machine isn't as powerful as the HP or Dell, and doesn't keep a small footprint or have wireless connectivity options.

Asus

Last year, Asus changed the laptop scene by introducing the original Eee PC, an underpowered low cost laptop referred to as a netbook that focused on portability and battery life over performance and extravagance. Now, Asus has taken the same tact with the desktop and is selling the Eee Box.

The system takes the basic internals found in most netbooks, like an Intel Atom 1.6GHz processor, which is a low power chip, and adds in 1GB of RAM, a 160GB hard drive, Intel integrated graphics, Gigabit ethernet and integrated WiFi. Most notably, the machine doesn't come with Windows, and has a price of around $320.

We'd recommend the Eee Box as an internet surfing machine exclusively. With the small hard drive, lack of RAM and Linux operating system, the machine hardly fits most households. That being said, it does include WiFi and gigabit ethernet, making it an attractive machine as a second or third computer in a household, but probably not a primary machine.

Lenovo

When IBM sold off their computer making business to Lenovo, the brand immediately focused on IBM's strong suit: Notebooks. Now, the company has expanded outside the ThinkPad realm into the ThinkCentre line of desktops. Their low-end A61 model, unfortunately, is extremely underpowered and doesn't live up to the luster of the ThinkPad brand.

The machine's AMD Sempron 3600+ processor is a lightweight, and with a paltry 512MB of RAM, and an 80GB hard drive, the machine is one of the least powerful machines on the market. The machine does have a small footprint though, but the similarly sized Eee Box is $20-$30 cheaper and outperforms this machine in nearly every aspect. The big difference is the inclusion of Windows, which is likely the reason why the specs are as underpowered. Regardless, Lenovo should stick to making business desktops and great notebooks, and consumers should skip their low-end model desktops when there are better models around.

Our picks

For the most bang for the buck, we like Dell's Inspiron 518. It won't be as pretty as the HP, nor does it have the graphics edge that the ZT has; however, people looking to do basic computer tasks and "walk on the wild side" of editing photos or videos occasionally will likely find that the Dell is most up to the task. HPs slimline machine is a great looking, well designed machine that has adequate specs, and with an Nvidia graphics chip, it might fare a bit better in games than the Dell. However, the graphics edge goes to the ZT, with its GeForce 7050 processor.

People looking for WiFi and svelte size should get an Eee Box, while everyone on the planet should skip both Lenovo's and Acer's comparatively poor offerings.

Netbooks

While we're mostly talking desktops, notebooks are dropping in price too. The netbook class of computers has many options for under $500, but don't expect these machines to do any more than surf the internet. Netbooks are extremely basic and likely won't handle duties like photo processing and the like. Our pick for this year was HP's Mini 1000, but we have more in our 2008 holiday gift guide for netbooks.

[Image: Steve Wampler]