I'm running an Athlon XP at 2200+ under 98se. It's pretty good, but not flawless. I notice some jerkiness, but it doesn't affect game play.
Now that analog+ can do multiple mice in WinXP, I have no reason to stay with 98se (other than I don't own a copy of XP yet). I'm looking forward to better Daphne video.
YMMV,
Rocky