Newer drives often are more efficient than older, more primitive drives. As heat is the result of waste/inefficiency, newer drives generally run cooler, all else being equal.

thanks @jerv , I agree; so, the difference between 320GB / 500GB / 1TB should be meaningless? Im worried that the processing from the notebook may create a bottleneck between the drive and data flowing, thus heating up the drive again… Or, maybe, the new, faster drive may optimice the processor use, improving general performance…

I’d worry more about cleaning the heat sinks. Laptops have small heat sinks anyway, so even a little fuzz or cat hair in there can lead to overheating; they’re less forgiving than desktops because of their size. Even if it doesn’t truly overheat, higher temperatures will cause things to throttle down in order to reduce heat generation.

Just keep it all clean and you should be fine. Besides, the biggest heat generators are the CPU, GPU, and battery; hard drives run quite cool compared to those. In my system, the hard drive is 20–60 degrees cooler than those three.