If you didn't create your required HP Recovery Disc set when you first setup the computer and it didn't come with Windows 7 Recovery or Restore media, contact HP to request this media.
I would still download and run "RWEverything", to determine if the the BIOS is has SLIC v2.1... as this is necessary to pre-activate any OEM SLP (system locked preactivation) syatem. If the BIOS is SLIC v2.1 and you can get HP recovery discs that use SLP... you will use the discs to recovery your computer, then ABR to pull the key and cert, then install Windows 7 Pro (don't enter a key during the install), then ABR to restore the key and cert. After this you should be good to go.
Lesson learned... ALWAYS CREATE YOUR RECOVERY MEDIA AS SOON AS YOU SETUP YOUR COMPUTER... ALWAYS!!!
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