I would say buy the computer from elsewhere. With the deals on the net, stores etc youre almost certain to find a better deal. Also, you can get whatever you want and arent forced to choose b/w an IBM or Dell.
But if you have to buy it from the schoo, are lazy to research buying it elsewhere or whatever, id say go for an IBM. The Dells seemed to be plagued with problems here. Not to say that IBMs dont have their share of problems either.
The school gave the Tungsten E this year and I think its gonna be E2 next year. The one they give is more than enough but if you want extra features, buy your own.
Hope this helps.