Your agp card doesn't have agp output port. What does the manual say about output ports that you have. If you have a dvi output connection, then all you need a is a cable that has dvi connector in one end and hdmi connector on the other end.
I've got a HD TV (HD Ready (720p / 1080i) ) and i have it hooked up to normal TV, and then i have a AGP cable coming from my PC (ATI Radeon HD 3650) to the AGP port on the TV. thing is when I'm watching video on it, i get black lines moving up the screen. and i don't like it. currently i had a dvi to agp converter for the cable, but i was wondering, if i got a dvi to HDMI converter instead, and plugged into the HDMI port of the tv, would i get a better picture quality?