1) Your direct-x should be ok. Windows XP uses 9.x which is fine.
2) As you have an AMD processor: try reloading your motherboard drivers. These drivers instruct windows in how to use the motherboard properly. One of the areas that tends to be 'reprogrammed' is the AGP/graphics handling code and if these AGP 'updates' are not present, you sometimes find this will screw up high performance 3D games and cause glitchy results.
3) If you haven't done so already, unplug your connection to the web. Try running NWN now.
4) Are you sure you're not using the standard Windows XP graphics drivers? These are notoriously bad when using applications/games that use the 3D side of your graphics. Try and find the original driver CD for your graphics card and install the driver from it.
5) Desperate Action: Try uninstalling the drivers and re-installing. To do so follow these 'guide-lines':
Boot the PC.
Before the windows logo appears press F8. A menu will appear. If the logo
appears, you've missed it and will have to reset your PC and try again.
Choose 'Safe Mode'.
The PC will probably take a fairly long time to boot. When it has, don't be
alarmed at the terrible screen resolution.
Now click on the following:
Select 'Device Manager' from the window that appears.
You will now see a list of catagories. Click on the '+' next to
'Display Adapters'. You should see a list of display drivers unfold.
They should say something like 'Nvidia GeForce2 MX'.
Now this is important: Click on each of the items under 'Display Adapters'
and press the 'Delete' key. Confirm each deletion as you're asked. Do *not*
delect and delete anything else.
When you're finished, click on 'OK' to get rid of the window.
Reset your PC (you may be asked to do this anyway).
When windows boots, it will be in normal mode and *may* ask you for a driver
CD. Cancel the message.
You have two options now. You can run your original graphics card driver CD
*or* you can run the driver EXE that you downloaded from Nvidia's website.
6) Almost very last suggestion: Reinstall Windows XP 
7) Very last suggestion: Jam 4 sticks of dynamite into your CD drive and blow
the muther up! 
Hope this helps!