I have used VMWare and Virtual PC before, and had more luck with VM. Still, 3d acceleration was pretty lacking, though I think there's some plugins for it to do up to like a 16mb card. In windows XP you can use a Glide/3fdx wrapper for those games that support it. Games like Pod and Dethkarz work great that way.
And of course, if you can, find a good 400mhz P2 and build a sweet Win98SE comp. I made one for $10 from parts from Goodwill. Voodoo cards rock.