It all depends on what you want to get, for under $800 you can get a fairly good system, but it probably wouoldnt be a really nice gaming machine. Its not that difficult to build a computer. For example, lets say you want to get a Pentium 4 2.4Ghz processor, most likely it will be a socket 478, then look for a mid-size motherboard that supports socket 478, then your processor and motherboard will be compatible. Then look for a motherboard that supports EIDE (they all have that) so you can plug your DVD Drives and Hard Drives into your motherboard. The case should be a mid-tower so you can easily add the parts to the computer and then you motherboard and case will be compatible. The rest is pretty simple, the most difficult part is choosing a motherboard and processor.
So remember these facts to build your own computer easily:
Motherboard should be a mid-ATX with socket 478 and EIDE
Processor should be a Pentium (you should get a Pentium with at least 2.2Ghz) socket 478
Case should be a full or mid-size to support your motherboard
Then choose the drives and hardrives you want.
Also remember that your motherboard should support DDR ram, then select your ram and make sure that your motherboard supports it. (DDR333 should be compatible with your mobo)
To get an idea for the price of this computer, go to
www.newegg.com and add every part and it tells you the price. For your price range, this is what you should expect:
Motherboard that supports at least 2GB of ram
Pentium 4 2.4/2.8Ghz
DVD-ROM
CD-RW Drive
Floppy
512MB DDR Ram
at least an 80GB hard drive.
P.S. Also make sure that you buy fans (most likely 80mm), cables, and make sure your case has a power supply or get one seperatly.
**If you dont understand what i just wrote, you should not make your own computer form scratch, either buy one form a retailer or go to a PC configurator (
www.cyberpower.com is good) and select the parts. Hope i've been some help