What is the best way to keep a folder synchronized with my USB drive?

I know there is a similar topic on syncing between computers, but I'm looking for an application to run on one computer that will sync a "document/file" folder with a folder on my secondary/external USB drive.

What would be the best solution?

I know I could use Dropbox & Live Mesh, but they use up bandwith which isn't very good when I drop in a lot of large files.

I'm running Windows 7, but I assume any solution for Windows Vista would work just fine.

Solution 1:

You could run a freeware synchronization program. I've used SyncBack (freeware) and I'm very happy with it. I use it to synchronize some folders to as NAS at home.

Solution 2:

I've used SyncToy from Microsoft in the past - although do note that version 2.0 does have issues with syncing to NAS devices.

Solution 3:

I use Unison with Windows/Cygwin as well as with OSX. SyncBack is a pretty good choice for windows though.