If you are using vmware server you can look into the snapshot feature to create a primary VM then take the snapshot as you have tweaked to your liking. Then you can utilize the snapshot manager to "revert" back to a clean vm when your project is complete.

If you are using the the vmware workstation then you would be best server to follow David's advice.

Virtualbox too has this ability and it is included free, so if cost is an issue perhaps that is a better choice. 

How can I fully automate the creation and configuration of a SharePoint virtual machine?
A toddler's food intake seems very little: only milk and water and some solid food. Therefore, from where does this energy come?
