It's easy to make a mistake when buying a cheap used laptop in New Brunswick, North Carolina or New Mexico. Many people end up spending a ton of money on something expensive that they'll never use to its full potential, while others buy something so small that they have to do expensive upgrading in a matter of months.

There's few things more disappointing than finding out your 6 month old laptop can't do what you want it to do, or that you don't really need that $400 graphics card to run Microsoft Word.

Don't just buy blindly. Hopefully this article will help you ask the right questions and get the right hardware for your needs in return.

Often overlooked as a component, your power supply is an important part of your laptop as it powers all the internal components. The power supply you need will largely be determined by the components in your PC - in particular CPU type, graphics card and number of internal devices.

For Pentium 4 and all AMD CPUs, a minimum 300W power supply is recommended. If you want to run one of the used ATI X8xx or GeForce 6xxx series 3D graphics cards, don't even try anything weaker than a 400W power supply.

Never overlook the significance of a power supply - an underpowered system will be prone not only to unreliable operation, but also to component damage.

On the entry level side of things you have a choice between AMD's Sempron CPUs and Intel's Celeron D. These CPUs are not for the hardcore gamer - they're for the average user who only want to run office applications and use the Internet.

For the hardcore user/gamer there's the Pentium 4 and the AMD Athlon 64 CPUs. There's little to choose between the two big guns in the CPU business. The slowest Pentium 4 CPU readily available at present is the 3Ghz version, while AMD's equivalent, the Athlon 64 3000+ will likewise satisfy most users' demand for processing power.

Go faster than that and the increase in cost becomes quite significant, and you'll have to weigh that up against your budget and your demands.

The most important thing to keep in mind when picking a motherboard is to get one that's fairly future proof.

For Pentium 4 that means a motherboard that supports socket 775 CPUs, and for AMD a motherboard that supports socket 939 CPUs. Also, make sure your motherboard has enough expansion slots (most commonly PCI slots) to support all additional cards you may want to use in future - including sound cards, TV cards, wireless network cards, etc.

If you're a gamer, also make sure that your motherboard supports either an AGP 8x (obsolete soon), but preferably a PCI-Express 16x slot for a 3D graphics card.

While most motherboards these days feature an onboard graphics card that is suitable for the casual user, these aren't adequate for gamers.

With the old AGP 8x architecture almost obsolete, the way to go is a PCI-Express graphics card if you have a motherboard that supports it.

For casual gamers who want to play a bit of Sims and Harry Potter, nVidia's GeForce 6600 and ATI's X700 series of cards will do the trick.

For the hardcore gamer who wants to play cutting edge games like Doom 3 and Battlefield 2 at rocking frame rates, don't get anything smaller than a GeForce 6600GT or ATI X800 with 256MB of GDDR3 memory on the card. 128MB is also acceptable if you don't want to play at resolutions higher than 1152x864.

Before buying a graphics card, make sure that a) your motherboard has the appropriate slot for it and b) that your power supply is strong enough to support it.
RAM is fast memory used by your laptop to execute tasks. When your laptop runs out of RAM, it starts swapping data to the much slower hard drive, which slows down your entire system.

With RAM being so cheap these days I'd recommend you get at least 512MB. If you're going to run Windows XP, don't get less than 256MB or you'll slow even the fastest CPU powered laptop to a crawl.

For hardcore gamers, less than 1GB simply isn't an option anymore.

The smallest hard drive you can buy at the time of writing is 80GB. That's more than the average home/office user will ever fill, while it's not nearly enough for music/video collectors or avid gamers.

At the moment the first big price jump in hard drives comes between 200GB and 250GB, so 200GB would be a great option if you need some serious space. Be sure to make comparisons if you need more space - for example, two 200GB drives are much cheaper than one 400GB, even though you get the same amount of space.

On the other hand again, two 80GB drives are more expensive than one 160GB drive.

It's also worth getting a SATA hard drive if your motherboard supports it. It's much faster than IDE drives, which are still abundantly available.

Fortunately CD-ROM drives have quietly vanished off the market, so you can now get more versatile DVD-ROM and CD-ReWriter drives very cheaply.

If you want to be able to write DVDs, naturally go for a DVD-RW drive, and make sure the drive you get supports double-layer writing so you can use the used 8.5GB double layer DVD discs in it, which is a whole lot of backup storage.

So, that's just a quick rundown of the things to keep in mind when buying a used laptop cheap. Fortunately it's almost impossible to buy a slow laptop these days - only gamers and other users of high-demand software need to pay special attention to what they get.