For what it's worth, I recently got a discrete graphics card. It
wasn't a necessity, but I'm happy with it, as I can scroll and pan
graphics much more smoothly. Compiz is also stable with it, unlike the
onboard video, where compiz was so unstable that I wouldn't use it.

I got a PNY/Nvidia GT9600 with 1G of RAM at Fry's for I think $49, it
was the last they had at the store, I suppose they were popular.