Seriously the vanila oblivion is a severly overated game, it has so many flaws that the gaming masses and journalists seem to ignore.
When it first came out I hated it.
However, some 3 years down the track with the help of a very dedicated modding community this game has been turned into one of the greatest games of all time.
Make sure you mod the lame bits out of the game as soon as oyu get it. To give you an Idea the base game is about 6 gig's and I have added a little over that in mod's.
Some recomendations.
Fcom convergeance (OOO,Warcry,frans, MMM…) Deadly reflexes. Quarls texture pack. (if you have a high end computer) Beautiful people Natural habitat line of sight mods for no popup (needs very high end pc) Supreme magika and Midas magic. Streamline 3.1