13 minutes... you won't do much better than you have already without losing loads of quality.
13 minute DV PAL, I'm guessing its roughly 2.8 gigs. MPEG1 could get you down to roughly 130 megs (VERY rough estimates; I have no idea what your movie consists of, or if its a good or bad target for compression).
Anyway... try Sorenson 3, and definately decrease the resolution.