NWN has been broken for more than a year. AMD doesn't seem to care. The solution posted above me is good, but don't use links you don't trust. Here's a safe and similar solution:
1. Go to the AMD Game site and go for the download section.
2. Select current drivers for your video card and OS.
3. Look for a "previous drivers" link on the bottom of the download box and click it.
4. You'll see a bunch of old Catalyst releases. Select 12.1 and download it.
5. Open the downloaded exe file with 7-zip and locate the atioglxx.d__ or similar file. Double click it.
6. Another 7-zip window opens where you'll see the atioglxx.dll file. Drag it to your NWN folder.
7. Now go and play.
CPU: AMD Phenom II X4 810 @ 3250MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 850/1100MHz | Display: L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 7 Pro x64
CPU: Pentium 4 Northwood S478 @ 3200MHz | RAM: 1,5GB DDR 400| MoBo: Gigabyte GA-8S661FXMP-RZ | GPU: ASUS Radeon X1650 Pro 256MB | Display: Dimarson 19" CRT | PSU: Noname 400W | OS: MS Windows XP Pro