HTC Desire :: Multitasking - Jump Between Running/open Apps?

How do I jump between running/open apps? Yesterday I was playing spades and chatting with a friend on google talk. It was terrible. I could not jump between the game and the chat. I had to hit home button, then menu then Google talk, to go back to spades I could hold the down home button and jump back to spades from the popup window. I could not do this with google talk from spades because google talk was not in the recently opened apps popup window.