After wrestling with getting AVWizard to work at all for a while, I finally got it running.
Unfortunately, if I select a widescreen resolution, it increases the resolution while leaving my display in 4:3 (squeezed into the center of the TV). That is to say, when I get to the "final" screen of the AVWizard, it lists my resolution (correctly) as 1080p, but lists my aspect ratio as 4:3. Once I get out of AVWizard, my desktop is, for lack of a better term, squished -- totally incomprehensible, can't even read the text on the screen.
I know my TV accepts 1080p from a computer, as I've done it in Windows (on this exact computer).
(I've tried 720p as well, since the help page on the AVWizard suggests that 1080 may have issues.)