The below command works for me in windows xp and windows 7, however I have a new build in windows 8 and it no longer works. It says "Invalid Drive Specification"
The p: drive is a mapped network drive. I think it has something to do with that because if I simply change the p: to e: (local drive) the xcopy command works.
I can change directory to the P:\ path from command-line, shrug...
xcopy %USERPROFILE%\Favorites\*.* p:\backups\%username%\Favorites\ /s /y