When you really break it down, most $600 or so hardtails come with the kit (or similar) that Chone is recommending anyway. For $600 you can get a Fisher Tass, a Rockhopper Comp, or the likes. Add the value of your Hardrock used ($150 or more I would think on eBay) and you've got a nice pile of money to buy a good bike with. There's NOTHING wrong with your hardrock, it just doesn't make sense to put that kind of cash into it.