I have always used 1024x768, 800x600 is squatty and is slowly being phased down (not out), as you will see by going to almost any computer shop. More and more websites push 1024x768 and designers usually design in it or much higher.
800x600 just does not give enough room and to be honest, once I get a new monitor, I will be moving up as my card supports upwards to 2048x**** so I say go with it

.