Howdo narattah,
WM codecs are installed with the installation of your WMPlayer. Being that I know that XP SP2 comes with at least WMPlayer 8 I suspect that when theWMPlayer 10 was uninstalled, the codecs went with it.
Seeing as WMPlayer10 won't install try version 9. This comes with the 9series codecs, which are almost identical to the codec series that comes with WMPlayer 10 (these are version 9.1 codecs). Failing that I'd try installing version 10 (or version 9) player through Windows Update.
...Failing that try version 7 player...(I have to say that the WM7 audio codec is very poor though)
You should be able to find the old player versions on the following Windows site page...:
http://www.microsoft.com/windows/windowsme...n&qstechnology=or search google for "windows media player 9 download"
...Failing that make sure that your original player is fully uninstalled and there aren't any remnants lying around and try reinstalling your chosen player again.
...Failing that maybe a OS build might be the most efficient way of solving this. I'd say that was a last resort type of thing (so you may not want to do that).
Hope this helps.