So, my computer runs like crap and system restore didn't work, neither did all the cleaning I have done. It took a lot of work but it's still junk. I know maybe it's old and crap but i don't want to buy new again.

Anyways, I dont have a system restore disc... it's an HP laptop.

On the bottom of the laptop is a sticker that says win xp home edition product key and can I use that key to make sure when I reinstall that I don't have to buy windows again? (wouldn't be worth 100 bucks for this thing )