Typically when you save office files, you probably place them in the My Documents folder (or on your desktop). However, if you are constantly saving to or opening from an alternate location, such as a network location you can configure this location to be available in your Microsoft Office (2000/XP/2003) favorites bar.

This article on LockerGnome explains the exact steps to adding a custom location, so check it out. From what I can tell, it does not work on Office 2007, so once I find the equivalent functionality for 2007, I will post it.