Synchronize USB hard drive between Mac and PC

I have a large (750GB) FAT32 formatted USB hard drive and two computers - a MacBook and a PC - and I want to keep synched and duplicate versions of my work folders (images, word documents, videos etc) on each device: the hard drive, Mac and PC.

To achieve this I imagine a folder synchronization software running on both Mac and PC (ideally the same software) which would sync selected folders between the computer and hard drive.

Does anyone know of such a piece of software?

Many thanks!

Yeah, it's new and it's call BitTorrent Sync, just came out of Alpha. It uses a 32 character code you create to create folder based sharepoints...on any computer on your network, without futzing with Preferences. Bittorent does all the work, and you essentially can create your own cloud at will, with any internal or external hdd's.

I suppose you could find folder sync software for both platforms and do this manually, but really those solutions are starting to wither in favor of cloud based sync solutions.

Does what you're looking for, just over the internet (with a persistent cache on your local machine in case you're not online). I've used dropbox to do this exact task for a couple years now, and couldn't imaging going back to a more manual/client based solution.

There are numerous services that offer this, with more storage than you need (5GB is typical). The most well known are DropBox, Google Drive, Box.net and SugarSync. I would highly recommend you look at these before investing in client software to do this.

edit: I just happened to run into a New York Times article that discussed this very issue. See A User’s Guide to Finding Storage Space in the Cloud

You might want to take a look at using FreeFileSync to sync between the PC and the hard drive and then using Carbon Copy Cloner to sync between the Mac and the hard drive.

However, a better solution would be to create a "cloud" with your own external drive. If you have a spare machine lying around that you could convert to a Linux server, you could create your own cloud server for free using ownCloud or Tonido, both of which offer sync clients for Mac and PC. If you don't have a spare machine or want a simpler way to do this, you can buy a PogoPlug or TonidoPlug which essentially turn any USB drive into a NAS (Network Attached Storage). PogoPlug offers an easier to use interface, but TonidoPlug is more extensible. Both of these offer sync applications as well.