It depends how experienced you are. Personally, I'd go into the Bios (press F2) and change the boot sequence to utilize the DVD drive first. Then place the system restore disc or any OS disc and see if it starts. If it does then you know the other hardware is okay. Or you could hook up a hard drive from any other functional computer. It won't load Windows but it will try and lock up (due to drivers). But then you know it is merely the current hard drive. HD are simple to replace. Buy one online (New Egg preferrably) if you can wait a few days. Let me know what you find out.
I can't recall that model in particular but some HP BIOS's have a hard drive test. While its most likely dead you cantry and see if that model has the test and run it. 6930p's may still be under the initial 3 year warranty depending on when you purchased it, so you may want to go that route rather than purchasing a new HDD. You can verify your status by googling the terms "hp product warranty check".