Download Dropbox
JPE Launcher
Dropbox is software that syncs your files online and across your computers.
Put your files into your Dropbox on one computer, and they'll be instantly available on any of your other computers that you've installed Dropbox on (Windows, Mac, and Linux too!) Because a copy of your files are stored on Dropbox's secure servers, you can also access them from any computer or mobile device using the Dropbox website.
I have a list of needed components there for referance,please read it.
Only during install does the program seem to make any registry entries
The jpe portable should not interfere with any installed versions of Dropbox.
If you set up your dropbox with a custom sync folder other than My Documents Location
and you want it sandboxed, make sure the name and location are reflected in the jauntePE ini for redirection.
I believe the user will need to "delink" the machine using the Dropbox options (systray menu) before closing the app if using on multiple machines.
I would suggest using Empathy or some other exe lock to secure your launcher with a password because you will be automatically logged in.
Here's an AutoIT version posted here at TPFC awhile back to check out

There is another portable version in the Dropbox forum but it requires dotnet.