You would have to switch your designation for primary and secondary in order to do what I think you are planning to do, like Lord said. Ultramon does allow you to move things from one window to the next (works best in XP) but it requires items to be windowed.
Consider that you do have a lot higher overhead when your second display is active and your frame-rates plummet. Additionally you will have a lot of your desktop icons repositioned sometimes.
Yeah I know I tried that and it was messy, lol, I'm using Vista at the moment and the one good thing is that it automatically puts the black bars etc on the edge of games so I can play anything on widescreen but XP doesn't do that so that's why I was trying to come up with my original idea so I can go back to XP