I've searched various places, and can't get confirmation if SP3 for XP contains any updates/hotfixes for MCE 2005. I did find something regarding a problem with MCE downloading updates if SP3 has been installed, but thats it.

If update rollup 2, as well as one or two subsequent updates are included, it would really be a worthwhile service pack for Media Center

sp3 contains only updates for windows xp....
it doesnt contains any specific MCE updates......

Thanks for that info. Various other sites mentioned the possibility of MCE updates in SP3, and I was hoping they were correct. Anyway, thanks again.