I am booting windows 7 off of a solid state-- I also have a 1 tb harddrive ---- I want to make my games auto install to A: drive or my HDD---- I already auto put steam games there and utorrent and google chrome downloads into A:
During the install of a game or application, just choose the target drive. I'd recommend against a registry hack to force it to *always* go somewhere other than C.
In the Steam client you can designate wherever you want as the default.