I figured it out, though it wasn't intuitive.
The netbook worked fine when I connected it to my 42" 1920x1080 lcd TV, as far as recognizing the display and allowing me to set the resolution appropriately. With the Acer, that wasn't the case.
However, as I mentioned above, I have an ION2 in the netbook, and the NVIDIA control application let me set the resolution to 1920x1080p. It's working great now, though for some reason I don't have HMDI audio as a playerback option. That also worked fine on the LCD TV. I'll figure it out, eventually.
The netbook is an ASUS EE PC 1015PN, it does light gaming and 1080p video fine. Netbooks have come a long long way but still have some problems like slow I/O and heat management. That's off-topic, but though I would mention it.