This a possible fix for the error:
“Installation Failed
Setup must stop because the required package ‘Zune’ failed to install.
Custom Action 19:26:54:953: Operation ‘RemoveDriver’ has finished with result 0x80004005.
DIFXAPP: Rollback failed with error 0x2
Error code: 0x80004005
http://go.microsoft.com/fwlink/?LinkID=101253”
1. Download and run UnZoone which can be found here
http://remove-it.org/tools/unzoone Reboot your computer after running UnZoone.
1. Enable your Windows Firewall. If you get the message “Due to an unidentified problem, Windows cannot display Windows Firewall settings.” follow the instructions here
http://windowsxp.mvps.org/sharedaccess.htm to fix the problem.
1. Download and install the full Zune software package from here
http://support.microsoft.com/kb/944938
This worked for me. I hope it works for you, i tried everything before this and NOTHING WORKED, the second i tried this, it worked and installed fine and now its all good