I am running a 9600 XT 256Mb with AMD 2700+ and 1Gig of memory with no problems, just a small bit of lag in the bazaar/middle of an MGB party during primetime in PoK. No shadows (just like Mogur), but I haven't talked to anyone that is able to run with shadows on.
My personal choice is ATI due to two bad experiences with nVidia. Though I know several people that will not use ATI due to bad experiences.
Looks like you are doing your homework
I would suggest checking
Pricewatch for lowest pricing, just be careful with some of the companies that sell there as not all the companies are very reliable. Again, my personal preference is
NewEgg as they have reasonable prices and I have always had very good to excellent service from them.
Good luck in your search.
Weskat