On the outside chance that you're unaware of this, if you hit command-J when you're in Finder you'll be presented with, among others, the option to make you Desktop icons smaller.
Edit: I forgot to mention that you can schedule your Time Machine backups to your liking/needs, i.e. more or less often. (I don't run TM, so I'll leave it to others to advise you how.)
That will enable you to unplug your external so you can carry your Mac around easily. Of course, you'll have to remember to plug it back in at some point.
Last edited by artie505; 08/09/12 11:25 PM.
