In fact if you plan to stick with the Quake series you could switch to Linux, if not follow Chooco's advice and stick with Win for gaming.
I run Quake III in Win2K and linux, it feels about the same BUT ..........
If I run a timedemo with demo four I get 217 frames/second in Win2K and 243 in Linux, with the same version of NVidia drivers for my Geforce 3 Ti200.