Help for sims 2 Please :( !!!

A bit of help for the Sims
Hey guys,
Ok I wanted to play Sims 2 earlier, but I've lost a disc (i know that's stupid but.. oh well) And I was wondering if anyone knew if you could change the disc that you load up with?
I always load with the Sims Bon Voyage disc, and I have the university one and the pets one already loaded when i put that in, but I can only find the original sims 2 disc, so I was wondering if anyone knew how to change it so I load it up on that...?
:) Thanks guys xxx