Alright, after hours of Googling through other forums and websites, I've figured out that this is a fairly common problem with many NVIDIA cards, and that there are about 3 dozen different solutions floating around. However, most seem to be based on the premise that something is wrong with the S-Video to RCA adapter.
I know this isn't the case here for 2 reasons:
1) This exact setup worked with the old GPU (FX5200)
2) When booting, the ASUS splash and Windows loading screens are in full color. Its not until the drivers are loaded that the screen flickers and I'm in the land of 1950's programming. In fact, removing the GeForce drivers completely fixes the problem....except of course that I've removed my GeForce driver and am left with the basic Windows
I'm running 220.127.116.11 (release 06/01/06), and have tried rolling back to 84.21, 77.77, 77.72, and 66.93, the latter two being the drivers I used on my old FX5200 when it worked. And yes, the region setting are correct (M/NTSC United States in my case.)
Anywho, according to NVIDIA's FAQ section, the problem is that the NVIDIA manager is not "Auto-Selecting" the correct type of video out, and its a simple fix to manually do it through your NVIDIA Control Panel. But, oops, this solution was posted in Oct.2004 (viewed here NVIDIA FAQ #30: TV Out in Black and White
). I've attempted manually selecting S-Video in the Control Panel, with the results being uncchanged, and Composite, the result being a brief flash of color, then a dead black screen.
The other common solution offered is that the saturation levels are off (the claim being that the NVIDIA manager sets it to 0 (zero)). This has become as out-of-date as the above solution - almost all posts I found for it were dated early 2005 and before.
I'm sure there have to be other frustrated users out there. Let's see if we can't get a final solution to this once and for all. Thanks in advance for any help you've got to offer.
**searched computerforums using key's "Black and white" and "TV Out" - no relevant hits that I could see, but my apologies if I missed it**