I have multiple monitors, I am running a 32" LCD TV and two 19" displays. The " trick" is to match the resolution as close as possible. In my case the 32" TV is 1080p or 1920x1080, the aspect ratio is 16:9. The 19" monitors are 1280x1024, the aspect ratio is 4:3.
With this set up my vertical resolution is relatively close 1080 and 1024, and my "windows" stay about the same size.
The trick is to adjust your digital monitor resolution down to match your TV, usually, and change the size of the icons and task bar, so you have a similar look.
You can adjust these with either windows display settings/resolution or your video card control panel.
Here's a link to a video of my set up. http://www.youtube.com/watch?v=g8EusoPORfQ
I think this is what you are after.