10 mb????????? and you are not having problems already?
The video game gods must be smiling on you.
Before the patch 8500kb the gams started gettinb really nasty. By 1mb it was unplayable. The patch seemed to do a lot of good.
Fo3 was the same in the respect that the more that was on a save the more chance it had of freezing. It was never as bad as pre patch nv though IMO. I played nv on 360 and PS3, and it was just about the same deal with both systems.