Yes, the hd 7750 will max out all games at that resolution. Infact it comes close to maxing out all games at 720p and can play most games at high-medium settings @ 1080p. So hd 7750 will infact be an overkill for 800*600.
All you need for that resolution is a gt 630 or hd 6570.
And BTW why are you playing games at such an insanely low resolution??