hello…
ooh – to have it continually playing as a user navigates around, you have to have either flash doing the entire site or frames (so a hidden frame has the song and the site is in another frame – then as you navigate around the site in the one frame, the other frame plays the song…
i can’t say that, however, w/o noting that frames are typically considered a no-no:
https://www.google.com/search?q=html+frames+bad
and i’m also not so sure that you want music – it’s also sort of considered impolite to do to users, but i’ll leave that up to you and your client… 🙂
hope that helps!
sitruc