im going to school for motion graphicsand visual effects for movies. Now should i go with apple i book , or the power book.
i dont know its very hard to choose between the two of them.

What's your budget? If you can swing the Powerbook then do it. When messing with effects/composites etc., rendering times can be measured in hours if not days. So get the fastest you can afford. The iBook is a G3 while the PowerBook is a G4. Most of the graphical/movie software are G4 savy and it can make a significant difference. If you got a limited budget, get the 15". I would almost recommend getting the G5 tower instead but since you'll need it for other school work which require portability, then get the PB.

Other things you'll need:
Max out your RAM (but not from Apple, I prefer Kingston, more reliable and much cheaper)
External Firewire drive 80-120 GB (be very careful not to exceed 120 because you'll fall in a lower sustained write speed which is a big problem for video.
Firewire DVD burner - you can get an external burner for $300
Extra battery

just so you know though....I am planning on getting a powerbook 15" for college, but the existing model has been unchanged since last november....

The most likely announcement dates for new powerbooks (which are suspected to have 1.33 ghz g4's at the top end) are August 18-19 (one rumor site) or Apple Expo Paris, which is on Sept 16th.

Thought I'd let you know because if you buy any mac laptop now, it will be outdated in a handful of months, if not before.