I have a machine with a PCI 2.0 slot. The first graphics card I tried to instal was a Sapphire ATI Radeon 5450 which is PCI 2.1. The computer would neither detect nor drive it. At the time I was told it was not backwards compatible (I had bought it through a listing which incorrectly stated it was 2.0). Wound up with an NVidia GEforce GT 430 which works but is terribly underpowered, at least on my machine.
Would like to get more gaming performance out of my machine but have to wonder if I need a new system to do so. My current machine is running a dual-core ATHLON 64 3800+, four gb RAM, Windows 7 professional 64 bit. The graphics card I have actually ran faster under Windows XP 32 bit. Anyone have any thoughts on one that might do a bit more (and not cost a fortune)?