Yes you can pick and choose what you wish to copy.
It works similar to a backup program, or a 3rd-party CD Burner program.
Dave is correct about the toolbar entries. The registry features of SU need some TLC, automatic cleanup etc.
It's not hard to resetup the toolbars. Five mins max. Either put your old computer next to the new one for reference, or print out a screen shot.
The shortcuts are kept in the registry, but as Gaieus said there is a export/import utility built-in for those.
The ones you might wish to migrate, are the savings for WebDialogs or plugins.
The WebDialog keys all begin with "WebDialog_"
Unfortunately... there is no common prefix for plugin settings keys.