[Arkan]

Ok, if thats the case, get a black Antec case with a good power supply. Reuse your CD drives (doesn't matter if they're white because the Antec case has a door) You need to shop for these parts:

Antec case w/good PS
AMD Processor
Socket 939 Mobo
DDR 400 (PC 3200) Memory. (1G minimum)

You can get a Mobo with built in ethernet and sound card to shave some $$$ off from getting those. You'll have one tough decision to make though if you want to keep your video card. Your card is AGP.....newer Mobo's support PCI express now so if you want to upgrade in the future with the same mobo, you'll need to spring for a new PCI express video card. Thats what i would do. I would get a new video card.
That may put you over the $800 mark.