I was recently working with Creo Parametric (3d modeling software). Unfortunately, my VMs are not powerful enough to run this software. Solution? Steader State. Basically, this software let’s you do a P2V conversion and then by using the VHD boot feature of Windows 7 Ultimate/Enterprise, it will create a difference VHD to your base VHD. Upon booting Windows 7, you get two options: Rollback Windows and Windows 7. Pick roll back Windows 7 and bingo: you’re back to a clean state! This does require wiping out the contents of your C: drive however, so you will want to do this on a second box.
I found something better/easy for this process: Reboot Restore Rx (http://www.horizondatasys.com/en/products_and_solutions.aspx?ProductId=18). Only tested on XP, but it works great! You can toggle it on and off from the taskbar.
– Soli Deo Gloria