I do not want to back up my entire computer, just iPhoto and iMovie to the Time Machine.
TM is designed to Backup your Entire computer.
Time Machine > http://support.apple.com/kb/HT1427
I do not want to back up my entire computer, just iPhoto and iMovie ...
Get an External Hard Drive and make sure the EHD is Formatted Mac OS Extended (journaled)...
See here for > Format, Erase, or Reformat a drive
Then Drag and Drop the Complete iMovie and iPhoto Libraries from your Applucations Folder the the External Drive.
See therse 2 links on Backups...
The SAFE MAC Backups