So I have a pre-built machine that I bought about 2 years ago and I have my actual gaming PC now, I was wondering if I could use my old pre-build hard drive (I already have windows installed on my current hard drive), could I just erase the information off of it and use it, I have tried this before but it loads the information on the old hard drive not the one I want. I didn't erase the information though, is it this simple? Thanks for help.