I think you need the original install media. Boot from it and then something like this [copied text from another site - I searched for "Reinstall Windows Keep Files" - NB I think only the]
"You could do a custom install and recover the data from the Windows.old folder.
Boot from the Windows 7 DVD
Click Install Now
Accept License Agreement
When the option is displayed to select an installation type, click (Custom Advanced)
Select the disk partition where you would like to install Windows 7 Click Next.
You will receive the following warning:
The partition you selected might contain files from a previous Windows Installation. If it does, these files and folders will be moved to a folder named Windows.old. You will be able to access the information in Windows.old, but you will be able to use your previous version of Windows.
(At all cost, do NOT click anything named Format or Delete or Partition. So even doing a custom install, your personal files are still preserved.
Setup will now start the installation. During the installation, your machine will be restarted several times.
When the installation is complete, you can complete the Out of Box experience such as selecting your laptop, create a username, password, your time zone. You can then proceed to download the latest updates for Windows and reinstall your applications and drivers.
You can then recover your personal files from the Windows.old folder and reinstall all your applications and drivers."
However, to get your data beforehand, I'd burn a Ubuntu Live CD/DVD and boot from that. That should allow you to access your drives and copy stuff off to the external and/or laptop. If the other data drives are not corrupted in any way and don't hold any Windows files, then I'd just disconnect them until after the OS is installed then hook them back up and turn the machine on [maybe let it get it's updates first] - they should just remount.