I now have built three VPCs to be used as bases for various testing. I can make a copy of a VPC and then use that copy to install "dangerous" bits - eg betas, ctps etc.

My first VPC is a clean Windows XP SP2 system with all of the current updates.

My second VPC is that plus .NET 2.0,  VS2005 RTM and SQL Server Express RTM. I can the throw things like Atlas or WinFX on top of them. It took quite a long time to install this. So I won't have to do that again.

My third VPC is #2 PLUS the WinFX February CTP Components , SDK and VS2005 Extensions for WinFX. I plan to experiment with WCF (and need a very clean copy of this for a DevConnections session) with and without Atlas installed on top of it (ergo I want two) and also WPF.

I spent about two days creating them and then tucked them away onto my 200GB drive. Then I can make a copy on my external hard drive and go to town.