Well I'm a step closer now. I've messed around with Powerstrip so much I can barely see straight but here is a hack that at least works (although it isn't the most elegant solution).
I found that Powerstrip can be run as a service before users login (that is, the service runs before users login or autologin). So I set Powerstrip to load as a service. During the login screen, the screen still does not display a proper 800x840. It just goes into a funky 640x480 with the screen off-center. Windows (at this point) thinks it is 800x480, but the screen says it is 640x480. But Powerstrip is set to "Auto-Load with Windows" and "Restore Settings on Startup." After login, windows thinks for a bit and then loads Powerstrip. The screen refreshes into a couple of different resolutions and goes blank for a sec, then it finally refreshes into a proper 800x480. So doing it this way ultimately works!
My problem is that I'd like it to get to a proper 800x480 faster. Here is what doesn't make sense: whenever I go into Display Profiles and add the Advanced Timing Options listed on teh Xenarc website, my monitor quickly refreshes into the proper 800x840 - it works. BUT, when I restart (not using the services hack described above), the resolution is listed as 800x480, but the monitor displays teh funky 640x480 resolution. Powerstrip loads fine and Preferences are set to Auto-load with Windows and Restore the Display Settings on Startup, but the resolution is not restored.
Now, if, after a restart, I then open up Powerstrips's Display Profiles Configuration, the screen immediatly refreshes and starts to show the proper 800x480. This occurs simply by opening the Display Profiles Configuration dialog, nothing more. This tells me that Powerstrip is not properly loading my custom timings when Windows loads, but it does load the proper timings whenever I open the Display Profiles dialog.
There must be a reason for this. Why won't Powerstrip load my Custom Advanced timings when it loads up normally? Why woudl it not work when Windows loads and then work immediatly when I load the Custom Display Profiles dialog? The search continues...