Creating 5.1 Surround DVDs

[waldodiodio]

I have an HD cable converter with a digital audio output (optical audio). I'm not worried about the video being HD, but I'd like to retain the 5.1 surround audio when recording content on to my PC to made DVDs from. Is all I need a sound card that records digital (5.1) audio? Typically I capture AVI using Virtualdub and compress the video using TMPGEnc. Of course, I can just encode the video portion in TMPGEnc and reattach the audio later (which I do in Ulead Video Studio). Do you have any recommendations for the least expensive audio card that will allow me to capture 5.1 audio? Do you have any guidance as to the easiest way to make a 5.1 DVD from content captured from my cable converter box (Software / Procedures)?

System:
Dell XPS2 3.19 GHz Pentium 4, 2.0GB RAM
Windows XP
Video: ATI AIW 9800
Sound: Creative Audigy 2 SoundBlaster with SB1394
Software: VirtualDub, TMPGEnc, Roxio Creator 8 Suite, Ulead Video Studio 10, Sony Sound Forge 7.0

[Baldrick]

See https://forum.videohelp.com/viewtopic.php?p=1637114#1637114 (but you don't need to use the optical input)

[waldodiodio]

I just realized that my HD DVR has firewire 1394 output and my Audigy sound card has a 1394 input. It sounds like I'm in business. I hate to sound ignorant, but if I connect my HD DVR to my sound card using a 1394 cable, if the source is in 5.1, will the sound file I create be in 5.1? Is there any specific software I have to use to record the file? Will it be a WAV file? Can I attach the audio file to my video in another software (Ulead Video Studio) "as is" and it remain in 5.1?