Easiest way to reinstall Windows 7 OEM?
 

I need to reinstall an OEM version of Windows 7 on a dual boot computer. Problem is, the OEM reinstaller wants to format the entire disk, and I have 3 linux partitions (/,/home,swap).

What's the easiest way to do this without needing to reinstall, and reconfigure Linux afterwards?

How are you trying to reinstall? Are you trying to use a Recovery disc? Or do you have an actual windows 7 full installation CD/DVD? I would be surprised if that was the only option but then, I've never installed windows 7 so don't really know the options.

Yep, OEM installers tend to be some drive image and can change partition sizes.

What I might do is clone off your linux with maybe clonezilla or just dd or even tar/cpio command.

Then do the new windows 7 install. Then shrink the partition to the size or slightly larger partition that you have now for all of linux. Then copy linux back. Then fix boot loader.

That's why I run one un-disturbed host operating system and everything else as guests. No "dual booting" for me anymore.

This is not a feature of Windows 7, it's the way the OEM manufacturer has it set up, and indeed the way most "restore" installers work. I assume you're trying to restore from the built-in restore utility using the restore partition. This will indeed reformat the whole disk, and restore it to "as new" condition. Installing from either an OEM or retail DVD gives you complete control over the install process.

OK, I would agree that the virtual machine idea sundialsvcs suggests is a good solution too. Clone off your linux and re-create it as a virtual machine client under some virtual solution with the windows as a host.