Here's the deal: I currently have a non-HDTV Sony (Wega KV32FS13) and a 7.1 system. I currently watch programs on analog cable, with average picture and stereo sound. Now I see these HDTV cards that can receive and output HDTV sound and picture. Would it be worth it to get one of these ~$300 cards? I would be using it for OTA HDTV only. Even though my TV isn't even HDTV-ready, I've heard that a lot of OTA programs are shown in OAR and Dolby Digital 5.1 sound. Is there a way to use these cards with my HT, i.e., can it downconvert to NTSC while keeping the aspect ratio and 5.1 sound?