u won't be able to do so while attached to the desktop, unless on wifi I think, can't remember is been awhile since I last actually synced with a desktop. the only way to use it as a charger only is to disable activsync if I'm not mistaken....and theres a program in the software section, that someone posted recently I do believe that will do this for u with the press of a button.
hope this helps.
~mike