Down side of buying a used copy of Elders Scroll IV: Oblivion?

Thinking of picking up a used copy of the game from a reseller with a pretty good rating but curious if there is any downside to buying the game this way?

 Will I have to deal with a cd key for the game? Will I have to activate the game online in order to play offline? 

Is a CD key needed in order install expansions? 

Or is pretty much the original CD/Dvd the only real issue I have to deal with in order to install and run the game (with it in the drive)?

Any other issues I might have to deal with or would I be okay picking up a used copy of the game?

Thanks. 

u can also avoid buying it inorder to save some money.ycdeo

[QUOTE="ycdeo"]u can also avoid buying it inorder to save some money.SuperBeast

A) Filthy lies.

B) The worst ES game is still better than the majority of RPGs, much like the worst Mario game is still better than the majority of platformers.

[QUOTE="SuperBeast"][QUOTE="ycdeo"]u can also avoid buying it inorder to save some money.TheChronoMaster

A) Filthy lies.

B) The worst ES game is still better than the majority of RPGs, much like the worst Mario game is still better than the majority of platformers.