I wanted to put together a custom computer as I had heard some rumblings about custom cases, overclocking and water-cooled CPU's. I went to the local used computer store and asked for a motherboard. They sold me a Gigabyte GA-K8VT800M. I love it! I can mail order it for half as much, though. Anyway, here are the specifications of the computer that I put together:
120 GB Sata drive
1 Gig DDR Ram
3400+ AMD Athlon 64bit processor
Nvidea 5200 graphics card (for Halo)
540 Watt Power Supply
NEC DVD player
I put all this together for around $800, which I figure is about 1/3rd what you would pay for a brand name machine with the same power. It works great.
I've run into some snags along the way, but that's what it is all about- learning by doing. I didn't want a turnkey system because that would have been too easy. Now I know how to load XP on a Sata drive, or that XP won't load on an old HD with an old os. Gigabyte onboard video will disable, but not for a PCI graphics card, only an AGP graphics card. This drove me nuts for a while, until I bought an AGP card.