I would go with the IBM/Lenovo tablets or one of the Toshiba tablets.
IBM/Lenovo make very good tablets, and they tend to be very reliable and durable.
Toshiba also makes quite a few different tablet PCs. They range from an inexpensive 1.5K$ to a pricey 6K$ if you get everything they offer... maybe even more than that.
I myself just bought a Toshiba Protege M700. I got a good price on it at 1.5K from a reseller. It was a very good buy in my opinion. I got 2GB of RAM, 2.10GHz Centrino core 2 duo with and 800MHz front side bus (FSB).
The thing is pretty durable, probably comparable to my dad's IBM that he bought not too long ago. It's also very light, and has an internal CD/DVD drive. I've never really used it much, but it's nice to have when you need it... where as with IBM/Lenovo, you have to run and get your docking base (which doesn't come standard with the laptop...) to rip your songs or burn your assignment that's due in 5 minutes to disk.
The toshiba and the IBM/lenovo both have the intel X3100 GPU in them. It's a good little chip that'll enable you to do anything from classwork to 720p HD video and mild gaming during your down time.
Another plus of the toshiba is that it has a built in webcam, something IBM/Lenovo has yet to offer on their tablets.
And what school is requiring tablets? (Just wondering...)
