[Closed] Complicated backup/sync strategy ideas please (serious geek content)

I'm hoping some of you IT lot might be able to throw a few ideas on how best to organise backups and synchronisation in the Grips household.

I have my photos and videos on a laptop. However I am typically using a work laptop, especially if I am away for work, which has a small partition dedicated to a personal OS (Win 8 in this case). Because the partition is small, I've got an external HD to store whatever I want to mess about with in the evenings. To all intents and purposes this external drive is the work laptop's second drive.

Photoshop elements and also the organizer (which I would like to continue using for consistency) are installed on both machines, so I would like my catalogue to be the same on both machines. Synchronising them whenever they are on the same network would be handy, and provide some backup. Now I think Mrs Grips has a picture library too on the home laptop (in Windows Live photo manager thing) which doesn't need to be synced, just backed up, and there's also some random personal junk that should probably be backed up too. Mrs Grips' work is on Windows Skydrive cos it's small.

I've got another non-portable external HD, and also a NAS that I could use for backup, and also a desktop PC not doing anything currently.

The desktop PC is Vista Ultimate, the work laptop is Win 8 preview, the home laptop is Win 7 Home Premium. The work laptop goes on the home network

SO

I am thinking of using MS Synctoy to sync both laptops to the NAS when at home, and connecting either machine to the external HD to do a Windows backup of the Photoshop catalogue when I remember. That way I'll have three copies of my working catalogue and a backup.

Good idea? Or overkill, given that none of the backups are offsite...