32000Hz instead of 48000Hz?

When I open the File Information window in VirtualDub, it says that the audio stream is encoded at 32000Hz instead of 48000Hz. I did not downsample the AC3 audio on either DVD2AVI (to create the d2v project) or BeSweet (to create a 96kbps mp3). Why is this? All the movies I download from KaZaA always have a 48000Hz audio stream. I followed Doom9's DivX 5 GordianKnot guide and always chose the 5.1 channel audio track, rather than just 2 channels. Also, I cannot tell any difference when I convert either a 5.1 channel AC3 or a 2 channel AC3 into a regular 2 channel mp3 using BeSweet. I did select the "LFE to LR Channels" option for the 5.1 channel. Is there supposed to be a significant difference in sound quality? Thanks for addressing my newbie questions.

Does OggMachine do the same automatic downsample as Lame? If so, what is the threshold kbps to keep the ogg track at 48000Hz?

nope. it doesn't.