download SyncToy for free
http://www.microsoft.com/downloads/details.aspx?familyid=c26efa36-98e0-4ee9-a7c5-98d0592d8c52&displaylang=en

Establish your folder pairing and sync name(“SyncTest”)
see:http://www.solo-technology.com/blog/2006/09/20/how-to-using-synctoy-to-make-a-nightly-mirror-of-my-documents/

run computer management console
event viewer/windows logs/system
find the media insertion event
“The Portable Device Enumerator Service service entered the running state.”
(You may need to clear you event log and eject/reinsert you media to trigger this log event)

In the upper event window, right click on the event and select “Attach Task To This Event”
Windows open “Create Basic Task Window”
Give your task a name and hit next
Event information is already filled in, next
Action should show “Start a Program”, next
In the Start a Program window, browse to SyncToyCmd.exe(or your chosen sync app)
Add arguments. If your backup pairing is called SyncTest, enter “-RsyncTest”. Do not add quotes, do not add a space after the -R, SyncToy command line(or maybe Windows 7) is case sensative so SyncTest does not equal synctest!
Next, Finish

You can run the task right from Task Scheduler to verifuy it works
Now the only other problem I had was running my laptop on batteries, in Task Manager under the conditions tab, uncheck “Start the task only if the computer is on AC power”, otherwise task will only run when AC is plugged in.

Also, as USB polls and disconnects/reconnects, this task will run every couple of minutes, actually kinda cool, it’s auto-syncing to the USB HDD all the time