You can switch between .h and .cpp easily with ff-other-file. Bind it to a key:

(add-hook 'c-mode-common-hook (lambda() (local-set-key (kbd "C-c o") 'ff-find-other-file)))

If the .h is in the same directory as .c/.cpp, then Emacs automatically opens. Otherwise, you prompt for the .h file. Once the .h file is opened, subsequent execution of the command switches between the two files.