I've played on both Win98 and Win2k. I was surprised to see no difference on fps (between platforms), no matter what drivers I used (GF2 MX). I'm perfectly happy with Win2k, but I had to install Win98 in order to get my CH-Throttle work (requires real dos). Installing and adjusting Win98 (with numbers of blue screen of deaths), I'm grateful to Micro$oft for making such a superb platform as Win2k is.
I had "alt tab" -syndrome too, but after changed my desktop and AH resolution to same, problems were gone.
Just go for it, you won't regret it.
NT compatible is good place to visit, if you wanna be sure whether or not your other games works under Win2k.