My old machine died, so I'm in the process of building a new one. Actually, it's built, just need to reinstall all my stuff on it. Windows Premium, 64 bit. Last night, began the process of getting NWN to run, using my Diamond edition disk.
You have to run the version 1.64 critical rebuild before it will even start. Probably doesn't like the 64 bit OS until you do that. Also I ran it in XP SP3 emulation.. (right click on the start icon and select properties to do this)
Runs just fine now. I will soon get all the POTM stuff installed and see how that works.