Actually I was just looking for the same info because I too have a 6600GT 128MB and wanted to see how it compared to the iMac I'm thinking about.
As it turns out (and
as you can see in these benchmarks for example), the X1600 Pro is pretty close to the 6600GT. Disappointingly, it's slower than the 6600GT -- a
mid-range card released nearly two years ago now -- in most games when run above 1024x768. According to those benchmarks, FEAR would be downright unplayable on the iMac.
I'm hoping Apple figures out that they need to update the iMac's graphics really soon. I don't know why they can't offer the nVidia option on the 20" like they do on the 24".
