This is possible, but any misstep could invalidate the workunit you are processing. The agent must be exited first by minimizing it and right clicking on its icon to get to the "Exit" choice. Then you would have to watch using the Task manager to see that ud.exe and the project process(es) have finished executing. Then the entire install directory could be moved to another computer that also meets minimum hardware requirements for the project. You would have to be careful not to run the copy on the original machine accidentally during reboot or logging back on, otherwise this could lead to the loss of the work unit and require re-registering your agent or even reinstalling it. That is why moving the files rather than copying them would be safer. The same procedure would have to be used to move the directory back. The screen saver would not work on the second machine unless the UD.SCR file is also copied in the windows directory. Having said all of this, it is not officially supported and you would be doing this at your own risk.

You could. The back and forth swapping is referenced as a "sneakernet" strategy since you are shoving floppy disks around. Another new-tech strategy is to simply run WCG on a flash drive, and move the flash drive from computer to computer.

The grid.org forum at http://forum.grid.org has more about it but it's really very simple. You are basically swapping everything in the WCG directory from computer to computer, but it's easily to forget what's going on. Watch your clock and reset the time if it gets confused. Don't forget to exit WCG before the swap and restart it after. MOVING the files from computer to computer would be preferable to keep both computers busy. It would even be possible or preferable to have UDMonitor on the internet computer. Slot 1 would be running as much as possible on that computer, and Slot 2 would be the swappable slot.
Then, you have to learn how to manage UDMonitor manually.

I tried it with BOINC, but since it is more closely tied to the registry, the clocks got messed up even more and I got some deadlines for 1900. Stay with the UD interface if you are swapping from computer to computer.

Someone, I cannot remember who at the moment, downloaded and installed the UD agent on one of those "jump drives" or "USB Memory Sticks".

All files on the jumpdrive (including the directory of course)

They just carried that jumpdrive with them and stuck in into which ever computer they were using. When they were ready to leave a location, they just shut down the agent and unplugged it the jumpdrive. When they got to the new computer, they just plugged it in and started the agent. Very slick solution.

I tried it when I was converting machines to BOINC. It worked very well.