hey. ive been looking at what you have been saying, and i think that you are in the same boat that i was. you want a PC that handles all of the games you play now, but dont want to spend a whole lot of money. i heavily suggest that you go with a motherboard that has PCI-E x16. There are a whole lot of great video cards that are PCI-E x16, and you can definately find one that is in your price range. also, go with a sound card, they are like 30 bucks and definately worth it. i would say go with the winchester 3000. it works fine stock and you can OC it fro your exesive needs. here is my rig. it does everything and more than i want.
DFI LANPARTY UT nF4 Ultra-D Socket 939 NVIDIA nForce4 Ultra
SAPPHIRE 100595L-BL Radeon X700PRO 128MB GDDR3 PCI-Express x16 Video Card
CREATIVE Sound Blaster Live! 24-bit 30SB041000000 8 (7.1) Channels PCI Interface Sound Card
AMD Athlon 64 3000+ Winchester Integrated into Chip FSB Socket 939 Processor Model ADA3000BIBOX
Kingston ValueRAM 1GB (2 x 512MB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered Dual Channel Kit System Memor