There seems to be a change in HP's over the past few years so that if you clean reinstall from boot to C and leave the 199mb System Reserved Partition, Recovery and HP TOols partitions intact, you can later run Full Factory Recovery or Minimized OS Image Recovery by booting F11.
Previously if you deleted, formatted, wiped or just clean reinstalled to C it was iffy whether F11 Factory Recovery would later boot to run.
It's still a good idea to make your Factory Recovery disk set, but if you have room to let those three partitions remain you have a more stable Factory Recovery method if you might ever need it via F11 at boot. HP Backup and Recovery Manager HP Recov DIsks - make another set Reinstalling Windows 7
Edit: The Minimized OS Image Recovery option also is about as close to clean reinstall as you can get using Factory Recovery, with only the HP Support Assistant, Recovery Manager and Wireless Assistant reimaging with Windows 7.