JakeR -
Don't want to burst you bubble, but if you look at pricewatch.com you can get this.
Barebones Athlon system - $ 299
ATI Radeon DDR - $75
Maxtor 40GB ata 100 drive - $90
PC133 512Mb ram - $ 75
Total price $539. Granted you have to buy from a couple of different spots, but if you look you could probably get them all from one place for less than $600 including shipping. You would then also have a full warranty. Of course you didn't mention a sound card, which I assume there is one, a SB Live would bump the price up another $100 or so. So my advise would be to check out pricewatch and spec out a system that is an exact match to what you have, then you can decided if its a good deal
Tim