First I would seriously look into a SSD.
Then you should look on you PC/Laptop for the official COA sticker with the 25 carters. On a laptop it might be in the battery compartment. Now take a couple of reads through this Tutorial. If you have that number you do not have to buy Windows 7 as long as you haven't changed the motherboard. Clean Reinstall - Factory OEM Windows 7
I would advise backing up all the things you want to save before testing the hard drive again. Sometimes do more hard drive test will do more damage and make it very difficult to get information off the drive.
This post is what I would do if I had your problem.
I'm no expert.