Repair / Reinstall Windows 7 on a dual boot machine

Hello,

I have Windows XP & Windows 7 installed on the same hard-drive
in separate partitions.

I would like to repair the Windows 7 installation or reinstall it from scratch,

Do I have to do something special in order to keep the dual boot functioning
properly ?

Thank you :)
Itay

Not really, you should be able to just format the partition and Clean Install Windows 7
to it from the booted Win7 installation media.

But we can advise you better if we see a screenshot of Disk Management - Post a Screen Capture Image.

In addition look over these steps for Clean Reinstall - Factory OEM Windows 7 which compile everything that works best to get and keep a perfect reinstall, even for retail.