Odd... the system is alright. THough I am wondering what kind of nwn.ini file you use. Thing is with Vista and my dual monitor it keeps crashing nwn due to it using a Vista basic 32bit display setting and I use 64
(running in a forced 1600 resolution though)
On my laptop (also vista) it works like a charm, happy go getting and kick ass.
Only thing I had to do was DisableIntroMovies=1 and it worked.
Did you check NWN forums on nwn.bioware.com too for the issue?