I run VPC 4 Win 98 on my G4 Cube - and it goes pretty well. I especially like the drag-and-drop deal between Win 98 and Mac OS.
As far as games go, I' ve only ever tried Cossacks (I recommend it, too!), and it's playable - albeit just. The comparitable speed to a PC with relation to my configuration of 450Mhz G4 @ 256Mb would be an MMX Pentium 2 233Mhz (or thereabouts).
Therefore, older games should run a treat - but tread VERY warily when attempting the big 3D jobbies unless you have a GOD of a G4, maxxed to the hilt.
Better still, wait for the Mac version of the game to stomp onto the scene, and frag your PC opponents online in a blaze of glory.
[Edited by kiwi_the_iwik on 11-06-2001 at 05:56 PM]