Ok this is probably going to sound weird, but here goes.
I fixed my problem. After reinstalling several times in different areas and creating new user profiles I still wasn't getting the folder in "My Games".
I installed the game to my definetely inadequate laptop, it did it no problem, so I grabbed the folder out of "My Games" and pasted it in the relevant spot on my decent machine.
Have just been playing a game for 3 hours, no problems.