If I had to choose just one episode (though I love them all) it would be the one in which Sheldon was computer matched with Amy. Who would have thunk it?
Oh, btw, just purchased season 5 dvd on Best Buy online for $8.99 this morning - free shipping!
Hahah. Reruns on tonight. Love this one, where Penny dislocates her shoulder falling in the shower and Sheldon has to drive her to the hospital. She then requests that he sing her "Soft Kitty" when he gets her back home and into bed.