You'll find me using a superior Apple product (17" at 6.9 lbs) in class (I also own a Sony VAIO), and either using my VAIO or the school's desktop for the exam.. I'll probably go with the desktop as I like typing on a real keyboard.
Considering everyones just going to be typing I doubt theres going to be all that much difference between an apple or an ibm laptop or between the guy using his super fly top of the line gaming laptop and someone using a $1500 dell.
The examsoft minimum requirements;
To run successfully, ExamSoft requires a 200 MHz Pentium processor or better laptop computer with 64MB of RAM, and at least 50MB of free hard disk space.