If you're worried about fps in NwN (or any game for that matter), have a load of programs running, download this little program called "FSautostart" (It's freeware, so don't worry about paying or anything unless you want to donate to the guy, it would be much deserved and money well spent) :
http://www.kensalter.com/fsautostart/
It's pretty simple once you figure it out (should take about 10-15 mins for you), what it does is, it allows you to look at what is running on your computer in the background that is ~not needed for gaming~ and set things to shut down when you start the program and defragment your memory. Now, doing this manually is Dangerous as hell, you never know whether you'll lock up your computer and cause serious damage, but the beauty of this is that you can tell it to restart the background ones again once (say) NwN is shut down. And if you turn off your PC after making a mistake, everything goes back to normal anyway.
You might be cynical, but i noticed a humongous difference - games have higher framerates, universally, in my tests, if only due to its defragmenting memory.
EDIT : Oh yeah, if you have any doubts or want to know how to get it to work (it's simple, honestly) then i'll be happy to help you out, just give me a buzz on IRC when i'm about