OK, so I've spent a fair amount of time putting names to faces in Picasa 3.5 but in a few days (hopefully) my copy of Windows 7 should arrive and I'll need to reinstall Windows.

So, does anyone know what I need to backup so that I don't have to re-enter all those name tags?

N.B. I'm on Windows 7 RC and know that I don't have to do a clean reinstall but I would prefer to.

Outcome:

I clean installed Windows 7 and downloaded and installed Picasa. Unfortunately, the download link on the UK Picasa homepage still pointed to Picasa 3.0 (rather than 3.5) which doesn't have face recognition. This scanned my photos folders and overwrote the picasa.ini files along with the people information   :¬(

Fortunately I'd backed up the photos before installing Win 7, so after uninstalling Picasa 3.0 (along with it's database), restoring the photos from backup and installing Picasa 3.5, I finally got my face names back.

Extra...

Google has now posted advice on how to migrate to Windows 7 and keep your Picasa database, meaning that it will not need to rescan you photos and will retain all information about then including name tags. They have a method for upgrading and for a clean install of Win 7.

Basically you need to back up:

"C:\Users\%username%\AppData\Local\Google\Picasa2"

and

"C:\Users\%username%\AppData\Local\Google\Picasa2Albums"