Video card or scan converter?

Currently, I have my HTPC set up with the primary display being a 20" 1600x1200 LCD. I use the TV out on my old nVidia FX500 to drive an RF converter which puts my HTPC display on channel 100 throughout all the coax in my house. This (and an RF remote) lets the HTPC be used from all of the normal TVs as well as the primary display.

My problem is this: I want the TV out to be an exact mirror of the primary display. You can do this with 'Clone' mode, but their are two major problems here: video overlays don't clone in place (just a black box appears), plus only a portion of the screen real estate is cloned. Ideally, I want something that will take my 1600x1200 UXGA output and scale that down to TV size, so I don't have to sacrifice quality on my main display. To this end, I've been looking at various scan converters, but a high end one that will do 1600x1200@80 to S-Video or Composite is pretty damn expensive.

Anybody know of any reasonably priced solution? A video card that does a 'true' Clone mode, with scaling and no video overlay issues? A reasonably priced scan converter?

Thanks!