I can't help those of you who have already erased the game and now want to reinstall but have lost your CD keys. You'll have to wait until the Bioware servers are back online.
If you want to do a clean reinstall of the game and you still have it installed, go to:
C:\\NeverwinterNights\\NWN
and open the file:
nwncdkey.ini
using notepad or any other text editor.
Voila! Your CD key(s),