Macbook to replace iMac

Looking for some advice regarding MB's and iMac's. Currently, I run an iMac 24", 3.06Ghz., 2GB of RAM, 500GB HDD, etc. I bought it last year, and I'm starting to regret not getting a laptop for portability, etc. Currently, Mom and Dad are looking to make the move to the Apple side, and they want a desktop. I'm seriously considering selling the iMac to them, and buying either buying high end MB or low end MBP.

Just some info on what I'll use it for, web browsing, school papers and presentations, some iMovie stuff, iPhoto, and iTunes. Nothing graphic intensive. Also, I would not lose the use of the iMac, as it'll just move rooms.

Also work during the 10 weeks of summer I have off school. With that money I'd buy external monitor, wireless keyboard, and external hard drive.

Any thoughts on this. Like I said, I wouldn't be using it for anything graphic intensive.

Thanks everyone. I got to stop in at Best Buy today and messed around with the MB's and MBP's. I couldn't tell that big a difference between the two when I tried out the tasks I'll be using. I loved how light the MB was. And the screen size is perfect for on the go, at least for my taste.