I have at least 2 virtual machines in VMWare:
-the reference machine
-the work machine
The reference machine has only a clean Windows install and all the utilities software I always use (anti-malware, dito, pdf maker, …). I launch it from time to time to update it.
The work machine was a copy of the reference VM and has all the software I need. I work with it keep it up to date. IF I have a serious problem (which I never had), I simply trash it, launch the reference VM, update it, then clone it to get a new work VM and re-install the few specific software I use (including Aspire). Generally much quicker than solving a serious Windows problem. Don't tell me it's because I do not know Windows enough. It's true, by I am comparing with problems solved by Windows IT guys.
When I need testing a beta software, an old application which is no more updated or seems not very reliable, I simply make a clone of the reference VM and test with it. If the software is interesting, I install it on the work VM. Then I trash the test VM. In any case, my work VM remains safe.
Maybe the sandbox functions of Windows allow testing safely, but I prefer this solution: better safe than sorry.
In addition, all my data is on a shared Mac folder, so it is automagically backed up by Time Machine every hour. And of course, I have other back-up disks.
W7 - Aspire 8.517