MacBook - Problems Connecting to TV with HDMI cable

I have 2 issues connecting a Macbook up to a TV. I thought I had researched this enough to make it work, but apparently I'm missing something. I am using a mini-DVI to DVI adapter and a DVI-HDMI cable.

(1) I have been completely unsuccessful in connecting it to the HDMI port on my Sony 26" Bravia LCD. All I get is a blank screen that says "Invalid Format" at the bottom. Audio does come through the TV speakers on the HDMI input channel using a 3.5mm-RCA cable, but I have never been able to get video. I have tried rebooting and adjusting the display on the computer.

(2) Connecting to a 42" Philips Plasma TV using the HDMI successfully transmits video, but I can't figure out where to hook up the audio cable so it will play through the TV speakers while displaying the video from my computer simultaneously. There doesn't seem to be an audio port associated with the HDMI input (perhaps it was designed assuming that audio would only come through the HDMI cable). Is it possible to play sound through the TV instead of using external speakers?

At this point, I don't know what else to try for either of these issues. Any suggestions/ideas/education will be much appreciated. Thanks.