Windows Briefcase that is designed to do just what you want.
Here is a link to its usage:
If you frequently work on files outside your main computer (using a portable computer, for example), you can use Briefcase to synchronize the files with their counterparts on your main computer when you finish working on them.
When you reconnect your portable computer to your main computer (or insert a removable disk containing the modified files), Briefcase automatically updates the files on your main computer to the modified versions. You do not need to move modified files out of Briefcase or delete the existing copies on your main computer.
Hi my name is Ben,
I am a college student who frequently goes back and forth to different computers to do, save, and print my work. I was wondering if there was a way to sync my flash drive with my computer at home so that I don't have to copy and paste random documents back and forth. I have a Treo that syncs and was wondering if there was an option like that, where the computer looks for differences between it and the device to transfer only what's needed.
Any help on this subject is greatly appreciated.