I'm fairly new to external displays: is the mini-DVI connector a proprietary Apple connector? I can't seem to find a DVI cable that connects to it except in the Apple shop.
I've seen a few third party adapters. Mini-DVI itself isn't some sort of proprietary Apple connector. Apple just seems to use it unlike other vendors. I've seen Sony laptops with Mini-VGA.
Are you sure Sony's mini-DVI is the same as Apple's? To the best of my knowledge mini-DVI (and micro-DVI) an Apple-only thing.
If you are aware of a third-party adapter besides the Dynex one, I'd like to see it. Dynex's appears to be DVI-I, but is actually DVI-D just like Apple's.
Something else that is weird is that the DVI-A part of Apple's mini-DVI port is not supported in Boot Camp (not in 1.1 beta, at least). What's the deal with that?