All the bad expierience which I learned in this forum, I did never had it!
But I use and used allways a own WindowsXP on the same PC especially installed for GS & other samplers, DAWs, notationprograms and so on.
I'm lucky with GS3.12
The most problems I had I got from installing and uninstalling demo software.
So I use Partition Image from Acronis. Every weekend I backup my working WindowsXP and I reinstall the last working partition if problems arises.
It costs me only have an hour a week and an external backup drive.