Actually, I haven't noticed, but my hardware is fairly robust (Laptop with 3.2Ghz Desktop CPU, 1G DDR2 RAM, 120G HDD) so it doesn't slow my machine down noticably. I have noticed that Win2K boots up much faster under my VM than it does on a couple of PIII machines I own.
Isn't ESX server a paravirtualization also?
Not sure, as I don't use the ESX product. I use the Workstation product, which has handled every OS I've thrown at it.
I love the workstation product also - I use it for testing and I run win2K, XP, SUSE destop 10, and NetWare on it.
Have you tried out their server product? That's what I'm using on my laptop (and generally in my group, though we still have one 'workstation' holdout). I don't fully understand why they are charging for workstation and not server right now. Seems weird.