800x600 would work fine with a 1600x1200 and still be sharp because 1600x1200 is an integer multiple of 800x600. It's where the pixels don't scale up precisely is when you have the problems. That said, new panels are pretty good about scaling and it might be good enough for you. Old ones used to just do crap nearest neighbour interpolation and it looked really nasty.

As Digan17 said, you just need to try it out. It may be acceptable for you.