I just called my local Apple authorised repair company and asked about putting a new drive in my MBP, which is currently a little small for me. I see you can get 500GB drives now for about £100 on the web, but the guy told me that it was a bad idea to put in a 500GB drive because of "heat issues". The biggest they would recommend is 320GB. I'm not sure about this, but as far as my understanding goes, the size of a drive doesn't necessarily make it run hotter. I don't see why a 500GB Western Digital 5400rpm SATA 2.5" drive would be hotter than a 320GB one. Any more than a 120GB drive would be hotter than a 60GB drive. Is he talking rubbish?