hey guys seen alot of people with this problem
its to do with realtek's newest HD (High Defanition) Audio codec 1.54 in XP not vista
the problem is that all sounds, sound tiny and strange
ie if your playing music it cuts out the main vocals and just plays backing vocals and music etc...
extremely anoying anyway after trawling through google with no luck i managed to tackle the problem myself
id heard that if u reboot windows without the speaker jack pluged in then plug it in once windows has started it detects it correctly and fix's the problem however this is not the case it doesent
the problem is alot easyer to solve just open your HD Audio effects manager open the Mixer tab and slide the playback bar all the way to the left or the right (playback bar is at the top left of the mixer tab) this doesent affect the speaker balance however it will fix the problem miraculesly
Enjoy!