There are dozens of threads on video cards. I suggest you do a search and read them.
I had an ATI card on my last computer, and it worked well. My new card is nVidia 9800m GTS and it has worked flawlessly with the new drivers.
Windows 7 is basically Vista with some of the things what didn't work removed. As near as I can tell, there is nothing new in it, but reports say that it is faster and doesn't have all the hassles of Vista.
