I use the same for external cleaning.
For cleaning from Inside use Vaccume cleaner to blow air In. Should you face problems with ram and other cards use a pencil eraser to clean the contacts.
I also use a Industrial grade quick evoporating spray to clean the contacts of the sockets.
well...shud a vaccum cleaner be used for doing the cleaning chores of the computer?...i heard somewhere that it can damage the parts of the system..be it the strong airflow or the ionic air flowing off it!!!!!!!