I, too, initially went with the codec packs. I think you mentioned ACE? That one had my computer all screwed up. The encoders that I was using would crash if I had that codec pack installed. I would definitely recommend uninstalling and then installing individual codecs. If you download movies with Limewire, I would recommend the DivX and XviD codecs to start.
As for the DVD codec, it will probably be listed as MPEG2. If you take a VOB file and separate it into video and audio (this is called demultiplexing, or demuxing for short) you will get MPEG2 for the video portion. Standard formats for DVD audio are Linear PCM (.wav format...uncompressed) or AC3 (dolby digital format).
That's too bad that there's a line to use the computer...
I just had cable TV installed today. That should keep the wife away from MY computer!