Mountainside,
I'd keep Realtracks separate from the OS drive. Less chance of losing everything should one drive fail.
And, since I think you are a Realband user, I'd go into Prefs in RB and set the 'Temp Audio Directory' to be on a drive other than the OS also.
Your C: drive temp area is the default, but if you move it elsewhere RB won't be trying to read/write to the same drive at the same time.

I do not work here, but the benefits are still awesome
Make your sound your own!