ATI or Nvidia chipset

Either one will work fine.

Strangely enough, you have an Nvidia chipset on your AMD mobo. Like ravenware said, either card will be fine.

ATI GPUs tend to work better with your CPU just by nature, but with an NVIDIA chipset, I guess it's just whatever you think has better bang for the buck.

Here are my points about the two companies:



NVIDIA:

Pro:

1) GREAT drivers and software
2) EVGA makes them (A great company w/ great support)
3) Very powerful hardware, overclockable pretty far
4) SLI usually works better than Crossfire
5) Work better with NVIDIA chipsets and/or Intel CPUs

Con:

1) Usually pretty expensive compared to ATI
2) HUGE cards that draw LOTS of power
3) Not a lot of MIRs



ATI:

Pro:

1) A few good companies make them (Sapphire is usually best)
2) Very good bang for buck
3) Smaller than NVIDIA cards and usually more power efficient
4) Almost every model features an MIR
5) Work great with AMD CPUs

Con:

1) Crossfire is usually a mess
2) Often have very poorly written drivers
3) Tech support is not always so great