I JUST upgraded a system.  MSI NEO4 SLI, A64 3200+, 512MB OCZ Platinum 2-2-2-5 1T, 1 Gigabyte 6600GT with passive cooling, 21 USB ports (with hubs), 2 80GB WD drives, 1 Maxtor 120GB drive all PATA no raid, 4 Firewire, 2 Ethernet (100Mb PCI, 1000Mb on board), 1CD/RW Drive, 1 DVD Drive, 1 DVD/RW, 1 Zip Drive.  Running ZoneAlarm Internet security suite in the background, and all normal services, etc.  This is my everyday set up.  No changes were made from when I start it each day.  Heck, the office scheduler was even running.  I did not re-install windows when I upgraded the MB, Video, Ram, and CPU.  I just plugged everything in and re-started it.
Latest Forceware drivers, all stock settings on MB and G card, and drivers and I got 3670 in 05.  
These cards seem to be pretty strong.