Having the best laptop/pc is still useless if u dunno how to manage ur memory. I have seen people who just switch on all sorts of programs that are not needed all the time. This uses up alot of memory, unnecessarily.
Besides tat its also not advisable to simply install games and junk programs.

As for Mac, in my school we have a few Macs too, but the Macs are really slow. They are G3s. And they hang constantly, thus giving me a bad impression on Mac. Not only that Mac version of many popular softwares seem to abandoned much of its shortcut keys.

Bottom line is get what u really like be it Mac or PC, what u can afford and invest in RAM, this is really important. 1 or 2 Gig of RAM is best especially for 3D programs. And also check if the software u need are available for Mac.