Windows XP SP3 Does NOT Support High Definition Audio...Just Fix it making sp3 to sp2 and install it

If your windows sp2 drivers doesn't installs to sp3 follow the following trick:

Received some comments saying the above fix didn't work for them, so I just went and
did some googling and found another solution which change the CSDVersion to SP2 so
that you can install the Realtek audio driver or other drivers of SP2. Once you're done with that, just remember to change back the CDSVersion to SP3.

Let's get on with the solution... see if it works for you.
1) Open Regedit and go to :
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows\CDSVersion

2) Double-click CDSVersion and change it to 200, then restart your system.
100 (hex) means its sp1
200 (hex) means its sp2
300 (hex) means its sp3
3) Install kb888111xp2.exe (Microsoft UAA-Universal Audio Architecture Patch which should be available from your
Audio driver folder)
4) Install audio driver
5) Change CSDVersion back to 300 (remember this or else you system will think it's still
SP2 and many SP2 updates may reemerge in your Windows Update, that's my logical
guess anyway )
6) Restart your system.