The 8600 is a great machine will all the right pieces (great screen as long as you don't get the Hitachi WXGA+, 7200 rpm hard drive, 333 MHz RAM), except for the touchpad, which is the device you use ALL the time. I found it extermely frustrating to use compared to the touchpad on my old Inspiron and returned it.
If the touchpad performance is not important to you, the 8600 is a good choice. I didn't find it to be too big or heavy at all. Otherwise, take a look at the HP nc8000, IBM T41p or R50p. Of course the IBM's are pricey, but are lighter for carrying around at school. You should be able to get a 10% student discount on the HP. There are many other machines that others will recommend that I have nothing against, I just don't know them as well (Sager, Asus, VooDoo, iBuyPower, etc.).