For sometime now I have been using Victual PC to run my virtual computers on my local computer, in the lat couple of year have many other only one has really worked for me, you guest it Virtual PC and Virtual Server from Microsoft.
Virtual Server 2005 is great if you are planning to deploy many VM's on one Server, in a corporate environment where you need to have a lot of VM's running servers ranging from Microsoft WSUS, Exchange, SharePoint, DHCP and any other OS's you can think of.
Anyway but to Virtual PC I'm currently running our WSUS and playing with Windows server 2008 which ROCKS BTW.
Over all MVP is the best tool for right now and allows me to work on other servers no matter were I am.
MS again you rock and make my life so much easer to manage.
Love you guys.