Installing sims 2 expansion packs? I understand that when you install a sims 2 expansion pack, you have to use the last expansion pack that you've installed to start up the game.. But I was wondering if that means if I wanted to buy (for example) Sims 2, but also wanted Sims 2 Pets (the expansion), could I just buy and install Sims 2 Pets alone? Or do I have to install the original Sims 2 disk aswell? Thanks.. Hope my question isn't difficult to understand.