Hyper-V Program Manager
A while ago I posted about running Diablo under Virtual PC (http://blogs.msdn.com/virtual_pc_guy/archive/2005/04/29/412428.aspx) - however at that time I did not post about running Diablo II under Virtual PC because of a problem I was hitting when I tried to do this. Namely - Diablo II was taking 15+ minutes to launch (and using 100% CPU in the process). I have no idea why this happens - however I did find that if you install the latest update for Diablo II from Blizzard (downloadable from here: http://ftp.blizzard.com/pub/diablo2/patches/pc/D2Patch_110.exe) - the problem goes away and the game runs perfectly:
I was even able to setup a multiplayer game with myself :-)
Diablo 2 is an old game, the way he is coded make him consume all the cpu ressource he can use. So the game will eat all the cpu despite your cpu power. Can't be changed. You may try to run it under virtual box ( forum.gmstemple.com/index.php ) wich will render D2 smoother than Virtual PC or VMware.