the best thing to do is just round up all the presets (pro channel presets, track templates, exc.)
the third party presets are the toughest because you will have to round those up in their respective folders.
you really don't need to re-download everything though. you can go to your cakewalk command center cache and save all the installers in the CCC downloads folder.
install new HD, install command center, copy installers from old HD and paste them in the CCC downloads folder.
when you start up Command center it will see the installers and only update what is a newer release.
this saves you the time of downloading sonar and all its content all over again.