Do a search on your hard drive. It should be in C:\Windows\System32, but it could be elsewhere as well. If there are multiple copies, remove or rename any older ones. (Just look at the date on the files.)
The DLL in question deals with application compatibility, and NWN is an older game, but I don't see why that would be causing a problem. NWN2 completely blows the original away; however, its system requirements are much steeper. You might not be abe to get a satifcatory experience with your laptop.
Also make sure that ALL of your laptop drivers (chipset, video, audio) are up-to-date and that your version of XP is at least Service Pack 2