At the moment, I'm very impressed with Virtualbox running in Linux. I've installed Win2K (and its service packs) and Office2K (and its service packs) in under 90 minutes. It is one of the faster virtual machines I've used.
Win2k fonts, however, look ugly and are very hard to read on a LCD monitor (something I did not have when I last used Win2k), so I went ahead and installed a copy of WinXP on another virtual drive for Virtualbox. It runs fine (and the fonts are so much more readable with cleartype), but I discovered that WinXP is huge. An install of Win2k (upgraded to SP4) plus Office 2K and a free firewall and antivirus program created a 1.7 gig virtual disk file. An install of WinXP (upgraded to SP2) with the same free firewall and antivirus program created a 6.6 gig virtual disk file (and that's without Office). Seesh.