Sometimes with the latest versions of XP and Vista, one of the Automatic Updates included is the Microsoft “Universal Audio Architecture (UAA)”, an update that adds compatibility to many HD Audio adapters, but can also conflict with the Realtek HD Audio deivce found on your EVGA motherboard.   By removing this update from your system, you should be able to install the Realtek drivers correctly.

1. Make sure that your copy of Windows is fully up to date.  This is for both XP and Vista.
2. Update the rest of your system to the latest nForce drivers from EVGA.  Even if it skips the Audio installation, you can finish that later.
3. Go to the Realtek website and download the latest drivers.  Make sure not to run it, just download onto the desktop.  (www.realtek.com.tw/)
4. Check your Device Manager.   
   1. XP:   Start > Right click on “My Computer” >  Hardware Tab > Device Manager
   2. Vista:   Start > Select the search bar >  Type “Device Manager” > Choose “Device Manager” from results
5. In the Device Manager, check for any yellow error icons.  If you see one that says “Audio device”, or something similar, leave that alone.
6. Look under the “System Devices” category.
7. Look for the “Microsoft UAA Bus Driver for High Definition Audio”.  If that selection appears, restart your system into Safe Mode.
8. Once in Safe Mode, go back to the Device Manager, and find the UAA Bus driver entry (refer to steps 4-7)
9. Right click on the UAA Bus driver entry, and click on “Disable”.  
10. Once disabled, right click on it again, and select “Uninstall”.   Go through the uninstallation wizard, and make sure that it’s fully removed from your system.  A restart may be required.  If you need to restart, make sure to get back into Safe Mode. 
    1. Back in safe mode, if a “Found New Hardware” wizard appears, DO NOT run it.  Simply exit out of it.
11. Go to the Device Manager and confirm that the Microsoft UAA is gone.
12. Now go to the Control Panel, and go to the Programs list.
    1. XP:   Start > Control Panel > Add/Remove Programs
    2. Vista: Start > Control Panel > Programs and Features
13. Make sure to select the option to “View Installed Updates”.   In the list, see if the Microsoft UAA appears.  The update number is (KB888111).
    1. If this driver does not show up in both the Device Manager, or in the Programs list, then it is successfully uninstalled.
14. Go to your Realtek driver installation file, and run the installer.  If it goes smoothly, it should prompt you to restart your system at the end. 
15. Restart you system normally, and you should now be able to hear the Windows welcome chime.