These days your better off buying a newer, faster, larger drive. The SSD prices on NewEgg are pretty cheap. And if you're using HORM you don't care so much about write speeds, just read.
Windows requires the hibernation file to be on the root of the system drive. Some people have tried to get it onto another drive, but I don't believe they were ever successful. I also don't know how that would work with HORM since EWF would no longer be protecting the hibernation file from writes.