I'm still staying with win98. It might be that XP is far more stable and has a better look and everything, but it's still missing the ability to be backwards compatible. Win98 has enough of a problem with this.
And you're completely right about Winfellow/WinUAE. Fellow does concentrate on speed which is apparent when you find lacks in the graphics here, missing collision detection there, not too good diskloading over there and so on.
As for crippling crashes. WinUAE has fed me a couple of those but I think they're fixed. I really should try the new version soon. Crippling here meaning that the most I'm able to run graphics wise unless I want to reboot is solitare and minesweeper. But that might as well be a specific problem with my drivers since I've had similar problems with other programs.