I haven't played this game, but anyone knows if there's an OST album for it?

I have played Oblivion, but not his add-on "Shivering Isles"..

There is no official album for it.. but my question is:

is there any new music inside the add-on ?
If not, you could stick with the oblivion soundtrack.

Unfortunately, no new music was added to the Elder Scrolls IV:Oblivion soundtrack with the add on. But then again, Bethesda has never really added new music with it's expansions. Sorry, to be the bearer of bad news. :(