You need a moded inf. Check the site where you downloaded the driver, every driver's download page has the link for the respective moded inf.
Anyway, I don't know why you want to install the 91.45. I think that at this point, the best driver is the 91.31. Every drivers after this one have been showing lower results on 3Dmar05 (I wonder why
). But I guess it could vary on systems. I have a M3438G.
Cheers!
/edit: I'm sorry, I forgot to mention that the driver with best performance is actually the 91.33, but for some reason, this driver either keeps my GPU fan runing all the time (impossible to disable it) or makes overclockings impossible to save (I forgot wich one of this issues occured to me), so the 91.31 is a better option, as performance is almost as equal, and doesn't has the mentioned issues.