What compression software is Windows Media Edition using?

I seen some compressed tv shows in WME. What compression software is it using? I am impressed with it’s size and quality output. Can you use this on windows xp?

Better you ask Mr. Gates people, but you can start having a look here:

http://www.microsoft.com/windows/windowsmedia/forpros/encoderse/default.aspx

thanks. Do you know much about compressing video?

Not that much, just the knowledge I need to capture/edit/author to DVD from camera (that unfortunately records using compressed DV).
The HD formats will require better and more performant encoders and I understand H.264 AV is likely to play an important role in the consumer/prosumer and maybe commercial market segments.
You can find some refs to it at: http://www.mainconcept.com/site/
as MainConcept is a well known name in video codecs and encoders