The reason I wish to revert to W98 is because when I installed ME my sound no longer worked. Tried different ways to solve problem but no use. If XP was installed do you think the sound would be restored?
XP will almost certainly correct the problem. but chances are you will have to update drivers for much of your harware.
But have you really got the memory and processing power to handle XP? Don't wish to be rude but it is unusual for an ME machine let alone 98 to be able to deal with XP satisfactorily. You'll need 256Mb RAM and it is really only effective on more complex tasks or with several programs running at 512Mb.
I presume you did check the drivers for you soundcard on the maufacturers website? ME has its foibles but sound shouldn't be a major issue, although this maybe the first introduction of Windows Media Player to your computer. I'd also check what is default program for Sound and also update WMP.