hi guys im planning to get a macbook pro 2.53 unibody shortly. i would like to know how do i test to see if the unit i get has a defected gpu? i see a few people suffering with their gpu failing after they play games(some on windows few on osx) for about 20 minutes. I need to check my unit properly because ill be going overseas in about 2 weeks so i need to use the time i have to make sure i have a fully functional unit. thanks in advance.