ok, I'll tell you how it usually works. Maybe it is helpful:
Windows XP (up to SP2) does
not have support for the High Definition (HD) audio bus. Audio codecs (like the Realtek audio chip) and modems that use the hd audio bus are
not found by Windows. There is no entry in the device manager (not even a yellow one).
The update KB888111_forSP2 must be installed in order to make Windows find the audio chip and the modem. After you have installed the hotfix, sound and modem devices appear in the device manager yellow marked since no driver has been found.
Sometimes, and I dont know why, the installation of the KB888111 fails. In this case, the entry "Microsoft UAA Bus Driver for High Definition Audio" is marked with a little yellow exclamation mark. (This has not happened in your case).
However, if the installation of KB888111 was successful, the audio and modem devices appear in the device manager.
Now you can install HD Audio Codec drivers (such as Realtek drivers) and enjoy sound.
Ok... in your case, KB888111 appears to be installed correctly but the devices dont show up in the device manager anyway. (Unknown device is not the sound card. The soundcard is something like "HD audio device").
I think there is something wrong with the KB888111, even if there is no yellow exclamation mark.
You could try the following:
Make sure that you have installed the right KB888111. SP2 must be installed and the KB888111 must be for SP2 as well (there is a not very well working version for SP1 as well). The hotfix is also dependent on the OS language. Make sure that you have fetched the right language version.
You can download it here
http://tinyurl.com/yvpaet
You could grab a beta version of SP3 for XP since SP3 will have the KB888111 included.
If you achieve to install any KB888111 that makes the audio and modem devices show up in the device manager, you have won
Regards
Borkar