If you feel like the problem is over heating, find instructions to open your laptop and clean the dust out. My laptop is 6 year old and is only in use when it's sitting on my lap, so to keep it running I open it up from time to time and remove all the blue jean lint that it collects.

I would agree with those who say reinstall Windows. Delete the partition and start over.

It's illegal to not give you a windows disc. You paid for it, you should have the disc. Of course places like Best Buy who don't give you the disc will happily reinstall windows for you at a hefty labor price. If you need a disc, I would be happy to point you in the right direction for finding one online.

Using Ubuntu is a great idea as well. It's free, easy on resources, and is the easiest Linux based OS to use if you are used to Windows. Oh, and fuck Apple products, Mac is Whack.