just to chime in with something pro-mac...
my late 2007 15" mbpro (2.2ghz, upgraded to 4gb) held up amazingly well throughout my program (unlike the brand new windows pcs that a number of my friends burned through during the program). a few of us had macs. by the end of our program, two of my buddies had taken the plunge, while the other few were just about to hop on board.
on the mac right now. it's almost four years old and going strong. need to update the hd (that'll be next weekend's project), but it's otherwise a solid machine. i actually prefer matlab on a mac and fusion allows you to run any windows programs you might have to run.
never understood all the hatred. from a TCO perspective, macs may be, in fact, cheaper. also, some people (i'm one of them) have a preference for the operating system. it has nothing to do with this:
http://stuffwhitepeoplelike.com/2008/01/30/39-apple-products/