It really is as easy as nhidalgo said, create a vm get it configured how you want then shut the vm down. Go to the file system of your VM Host (server) and copy the .vmdk files into another folder. Then when you need a new copy of that machine, make a copy of your copied .vmdk files and when you make a new VM tell it you want to use an existing .vmdk (hard disk image) and point it to the copy. You'll have a new machine configured how you want for your testing.
As said before also, you'll probably want to sysprep it to strip out the machine specific stuff like SID, machine name, etc. I also would not have the base image joined to the domain, that'll cause you grief as well, after you make your new machine with the existing hd image, sysprep it, or run newsid & change the name or whatever tool you choose to clean it up, then join it to the domain (if that is your intention).
h