Skip towards end for the partial solution.

Not long ago, I had LogonStudio Vista working enough to change my login screen.  I recently had to rebuild my system and re-install Vista (I'm using Vista Ultimate 64-bit SP1) and couldn't for the life of me remember how I got it to work the first time.  Googling around didn't help other than to show other people are getting the same errors. 

I would launch Logon Studio from Impulse, select the "Orange Nebula" screen, then press apply.  I then get this error message:

Unhandled exception has occored in a component in your application.  If you click Continue, the application will ignore this error and attempt to continue.

Method failed with unexpected error code 193.

See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.

Looks like I can't just use the pre-dfined screens and apply them...

So, I click on the Create button.  This brings up a dialog.  I type in a name for my logon picture, then click on Browse to find a BMP or JPG picture that I like, then click Save.  Pressing Apply will do just that- apply the new logon screen, but note that when you press apply, it will kick you back out to your logon screen, so depending on what you're doing, you may want to save and close any running programs.

Now I just need a way to use the screens it came with, I'm pretty partial to the Orange Nebula and Dark Avatar screens.