How to create a test environment for commercial Windows applications?

How do you best test commercial windows .NET applications on different environments? (XP, Vista, Win 7, Terminal server, Citrix) I was thinking of MS Virtual PC, together with some ghosting software like Acronis .. http://www.acronis.com/enterprise/ What are good, tested test setups ? :-) ....................................... Thanks to the help of volodi and lukas I've now come a bit further: It seems like VMWare Workstation is the perfect software solution for this problem. You can take snapshots of configurations, so we don't even need any imaging software anymore. Plus, it has a price of 189 $... sweet ... Now a few extra problems however we encountered : - In vmware, it is recommended you store your vm's on your LOCAL disk. Saving to a network or USB drive is possible, but you need PocketACE, and you'll have to store it first locally, then convert which seems cumbersome ... So we are thinking of buying a new laptop with 1TB Disk space. We would use this laptop solely for testing purposes. Where do you store your virtual machines ? -> Store it on a network drive or local disk... this was a misunderstanding ... - Now another problem seems backing up ... How you're gonna backup 500 GB of data ? That seems like a lot of work ... -> Well this was a misunderstanding. If you create a new machine, you have to allocate 40GB of space. So we thought, we need 8 machines, 8 x 40 = 320 GB ... This is wrong, a vm is +/- 3-6 GB ... The vm disk size seems to grow dynamically - Also, should i buy a 64-bit machine ? -> If you want to testCitrix XenServer, you will need a 64-bit processor ...