AGP, PCI, PCI-E 16x, PCI-E 1x, psh, IDE, SATA, USB, FireWire, serial, parallel, PS/2 video cards, none of any of that matters. TV signal is poor quality, end of story. That's all there is too it. All TV ('cept HDTV) signal sucks, it's all blurry low resolution interlaced analog crap. That is why the image sucks. The TV-output is for watching videos, movies, slideshows, not for reading articals and writing papers.
Your hardware is fine. It's the hardware standards that suck here.