OK, the way the Briefcase works is as follows:
Right click in the explorer window showing the contents of the USB key, and select New -> Briefcase. First of all, call it something different to "New briefcase" as this isn't very descriptive (select the briefcase and hit F2 or right click -> Rename). Now, double click on the briefcase and a help window should come up. This gives you more information about how the briefcase works. The gist of it is copy the files you want synchronised into the briefcase and take it home. Any modifications you make to the files at home in the briefcase will be stored (likewise any changes made to ones at work outside the briefcase). When you want them synchronised, simply plug the USB key back into the original computer, right click on the briefcase and select Update All. This will bring up another menu where you can select what is updated, whether the new file is overwritten by the old, or vice versa.
You can also individually update files by going into the briefcase and right clicking on an individual file and select Update
I'm not sure about whther this can work for synchronising the two computers, but it will definately synchronise the key and one computer, and this lets you work on the files on the USB key when using the other computer.
Hope this helps!
