If you don't allow 640x480 you're immediately losing a huge percentage of anyone who has less than a GF3. Even a decent gf2 will struggle with fillrate at 800x600 ( I've tested this extensively )
If you're not aiming at less than a gf3 then no problem. But there are a HECK of a lot of people out there with less than a gf3.
If you're not aiming at less than a gf3 then no problem. But there are a HECK of a lot of people out there with less than a gf3.