Not to get in the middle of the PC/MAC pissing match, but in the school system, them Macs are on par with the PC as far as repair time. Most times it's abuser, I mean user error. VirtualPC on the MAC and you have the best of both world.
I have a Dell Latitude D800, that is going on 3 years, only one warranty call, bad pressure point in the keyboard, (known problem), never had any problems with the LCDs and I move mine from home to work, and the cover is opened and closed at least 3 to 4 time daily. Battery life was around 3 hours new and now is between 2 and 3 hours depending on what i'm doing. Some of the older IBM thinkpads were crap, ether that or we got a bad run. We will be starting to use HP soon, the NB government made some sort of deal with HP for "Laptops in the Classroom" project.
Big thing is, as a primary machine, get spill and accident warranty coverage. The kids let one of the rabbits out and it cut my power cord, (Dell replaced under Warranty)
Hope this helps
James