Hello,
To be honest, I would consider purchasing a true Powerbook instead of an iBook for your situation. You said you wanted to do heavy graphics on your computer, and a full Powerbook has better innards (faster cache, faster motherboard speed) than the iBook that you will notice while performing larger image manipulation.
Also, the iBook and Powerbook both have video out. On the iBook, you have true video mirroring, meaning what you see on the LCD of the laptop is what will come out the extended port. On the PowerBook, however, you can do either mirroring, or have a second desktop. Having a second monitor is priceless for large working documents.
You will probably find Photoshop and other software at much reduced cost once you reach the university. I would plan on making the purchase there, as college students often get the best deals on hardware and software combinations. If you can, go to the college before you start your term, and see what kind of academic discounts you can find.
If you were just going to do word processing, and spreadsheets and such, a normal iBook would be fine. But with your plans, you should aim higher and faster.
Christian