Here's a really good analysis of 2001 BD vs. HD-DVD...
http://www.dvdbeaver.com/film2/DVDReviews33/2001_HD_Blu-ray.htm
Audio:
The HD supports the usual audio - a TrueHD English 5.1 track and a Dolby Digital Plus English 5.1 sounding duplicated to the 5.1 track on the SE - plus DUBs in French Dolby Digital Plus 5.1 and Spanish Dolby Digital Plus 5.1. The TrueHD sounded a shade more buoyant and pure playing Also Sprach Zarathustra or The Blue Danube and the rest of the score by György Ligeti. Dialogue audio is very consistent and supported by English, French, Spanish, Chinese, Korean, or Portuguese, subtitles, in a white font with black border (sample above).
Originally Posted by HighDefDigest 
"Warner gave us the first chance to do a head to head comparison of TrueHD vs. PCM... the results are in:
Out of the twenty comparisons (ten for him, ten for me), we could only detect differences on four scenes total. But of those four, we both always preferred the PCM track, if only a smidgeon."
Out of the twenty comparisons (ten for him, ten for me), we could only detect differences on four scenes total. But of those four, we both always preferred the PCM track, if only a smidgeon."
I think you're safe with the BD of 2001. It has a PCM track.