Using a spare HD as you did is a good way to run the WTP. No risk to your existing OS setup.
But, StnCld316, I had to chuckle at your last sentence...the one about bad sectors.
http://blog.gobbler.com/2012/07/hard-drive-myth-bad-sectors-and-reformatting/
I used to format every time I tried new OS's then formatted to go back to others and over time I have developed bad sectors and have had to replace the drives, so that's when I chose just to have an extra hard drive on hand for that purpose. Never had any more of them since.