A magnet *might* erase data. You can erase data yourself. Dropping it is to try to cause a head crash so the drive doesn't work. You should NOT cause physical damage to the exterior of the drive as I think some people think I meant to imply. You could send them the functional drive if you like, worst case scenario they try to charge you for it (about $1/5GB for desktops).
Also, I made my suggestion based on the assumption that this wasn't your only computer. If it is, simply leave it as is while HP mails you the new drive. Remember, they mail it to you first. Instead of breaking your current one, you may consider claiming that it makes funny noises. I exchanged one with them because I said the one I had was too loud. I had no problems with that.
Don't worry, they don't log calls in order to keep tabs on you and deny you service. They take examples of calls that went well and use them to train new employees.
Contact them through the online instant chat support and say your drive is making a weird clicking noise.