IME, the TV out on ATI cards just plain smokes nVidia's. I chose a cheap Radeon VE ($60) for my home theater PC output.
I seem to recall hearing good things about Matrox TV out, as well. They definitely have winning 2d quality.
Beyond that, you'd probably have to spend $100 or more for a hardware RGB to TV converter.
That's all I can think of for doing it "realtime" on a budget.
Otherwise, you have to transcode to DV, or mpeg 1 or 2, and output to a mini DV camcorder, DVD, SVCD, or VCD, AFAIK.