I couldn't really find a place to change the settings on it. I know you could do it in XP, but I don't know how in Vista.
I don't really see that much of a need for the system restore though. I haven't ever used it. Plus I don't have that much on my computer right now anyway. I would just have to install all my games and stuff if I needed to reinstall.
As long as you aren't using that 250 Gigs, I think it's fine. There really isn't a reason not too. I just liked seeing my free space go from 25 gigs to 35 gigs.