If you have a DVD player hooked up to your TV, then the only "fancy software" you need is (a) a cable that connects to the audio output of your DVD player and (b) a cable that connects that cable to the "line in" jack on your computer (which has a different shape).
If you have a DVD-ROM player in your computer, I'm not entirely sure, but I assume you should be able to capture from the DVD while it's being played (if you have a SoundBlaster card of some sort, I assume the "What You Hear" recording setting should be able to capture the sound).
If you can't get that stuff- which would be ideal to have- just put your microphone close to the speaker of your television and stay quiet while it records. I recommend turning off the speakers of your computer and muting "microphone" on your volume controls. That won't affect whether it's recording or not, but it will keep feedback and "static" to a minimum.
What Don said...I have a SB Live, and I don't have to mess around with controls - I just set it to record from wav ("what i hear" will also capture anything coming from your mic, midi, etc.) and it does it. You'll have to adjust the volume level yourself, though, which I find odd.