Minecraft wiki entry for Saved_data_Dropbox_guide, associated text: xcopy /I /E %AppData%\.minecraft %HomeDrive%%HomePath%\Dropbox\Minecraft
cd %AppData%
rename .minecraft .minecraft2
Note: attempting to use rename %AppData%\.minecraft %AppData%\.minecraft2 will give the error The syntax of the command is incorrect., as should be: rename %AppData%\.minecraft .minecraft2