I have Matrox Parhelia that has two VGA outs as well as a composite/s-video out. Works pretty well. I think Matrox has some newer/better/cheaper models that do what you need.
how do you use it? Can you keep both monitors active for editing and then use the TV out for Windows Secondary Display? or are you doing something different?
I'll have to check again, but I know I had Avid Xpress Pro running on both VGA screens and I used the TV out on the parhelia to feed an NTSC monitor. It pushed whatever was in the preview window in Avid, so I'd assume that it's the same in Vegas. I use a firewire card now to feed a DV deck-which contects to my NTSC monitor, so I'll need to test. But I'd suspect it will since it's a triple head card.
thanks for your feedback. Apparently (according to sony) if I try this in Vegas, I'll have to "capture" the part of the screen that I want to send out to the TV out. I don't know how great that'sll look or perform - going from a captured Video Preview to the TV...
so I think I'll go for a single VGA AGP card with a TV out and a PCI secondary vga card for my second monitor.
Are you using ASIO drivers with your sound card? Try using WDM drivers instead. I can never keep ASIO in sync while previewing in Vegas, but WDM is rock steady.