You should have a recovery partition on your hard drive, and when you boot up, IIRC, there be an option to recover from that partition.
The recovery software on that partition formats and restores the machine back to the original manufacturing state, so all the programs that were installed by the manufacturer would still remain. You'd have to have an OEM copy of Vista and install that to have a Vista without the manufacturer's software.
Soooo, you're saying I can't reinstall Vista...I can only restore it to the original state HP sold it to me as?!
I don't have an OEM of Vista When I bought my Dell with XP preloaded four years ago, it came with a seperate XP disc...