How can i tell if my copy of Elder Scrolls IV Oblivion has the shivering isles thing?

i bought the game a couple days ago and found out about shivering isles yesterday. how can i tell if my copy is the shivering isles one? is shivering isles only for PC?How can i tell if my copy of Elder Scrolls IV Oblivion has the shivering isles thing?
It does not include Shivering Isles. You CAN get Shivering Isles however by going to the Xbox marketplace and buying the download using Microsoft points. It's pretty expensive however. (~$30 worth of points) There's other expansions and add ons available at the marketplace as well, some free!How can i tell if my copy of Elder Scrolls IV Oblivion has the shivering isles thing?
Sivering Isles was a expantion pack its a totaly different box. And it would say on the box if it was or not. When you install the game it should say either install oblivion or shivering isles.