I've heard that I can use an existing triple front deraileur with a new double crankset I'm getting, is this true? I was just thinking that it would let me buy the new crankset and wait to buy a new derailleur (money's tight). Will this work? Thanks a lot.

Most likely, yes.

It may be a problem if it's an mtb derailleur meant for cute, little chain rings, but most likely it will work fine.