I am going to be purchasing a Macbook within the next week or so and will be upgrading the RAM and HD hopefully. I am looking into getting a 300-400GB HD 5400 RPM. I am wondering about some information regarding: 1. heat Is there a certain HD that will keep the MB cooler and less likely to burn my lap. 2. size I have heard that some HD's are a little bit different size wise and will be hard to fit in the MB. 3. space Will 120GB in a 160GB hard drive run slower than 120GB in a 320GB hard drive? (basically my main reason for purchasing the HD) 4. noise Which will keep the noise from getting too loud, I notice from my PB now that it will get a little noisy when running too many apps. Thanks in advance.