I figured out how to make it work. What I really wanted TV-out for was mplayer, which has a VESA option. To make that work I had to set my PCI Viper 550 card as my primary in my BIOS settings, and let my AGP geforce2 card become the secondary. Then I setup X to only use my geforce2 card (via BusID settings). This works surpisingly well. I have to switch to console to start mplayer (-vo VESA), but I can switch back to X and use it at the same time a video is playing. The only minor annoyance is that my text console is now on my TV. Not so bad though, since xterms are available.
I also got X to display on both my monitor and my TV at the same time using the new settings. I don't know why it didn't work w/ my AGP card as primary.