Disable Indexing and Superfetch and regular defrags (as per your choice). This should reduce some load on HDD.
I would just like to say that I do not recommend disabling any of the three. It's up to you, but I find superfetch gets everything up and running faster when I first startup Windows and even people with SSD's say they see a performance increase with superfetch on. Defrag should be left on so that you don't have to worry about your HDD becoming fragmented, which will increase HDD activity more than anything, and keep your computer running fast. Indexing I'm not as concerned about but it does speed up file searching. If you never use the search function than turn it of. If you do use it, leave indexing on.
