I'm planning to buy a new Canon SD-550 this week (Amazon is having a sale and my old 3MP camera is long in the tooth). I was checking out 1GB secure digital memory cards and saw that the Extreme III card is $15 more than the Ultra II. If I want to take lots of candid snapshots and the occasional short movie clip, is the upgrade to the Extreme III worth the extra dough? Actually, looking again... I think my mind is made up because the Ultra II card comes with a $25 coupon for prints at shutterfly.com. Still, any opinions on the cards or the camera? Save me from myself if I'm about to make a mistake.