I can't believe this topic appeared today when I just decided to look in to this yesterday.
I came across a couple of other options prior to reading this PPCT article:
etivo lets you automate the "archiving" of your shows from the TiVo to your PC. Pocket Etivo lets you then take the shows to your PPC.
Haven't tried it yet. http://prish.com/etivo/pocket_etivo.htm
Use TyTools to extract the TiVo shows to your PC then proceed as per normal for getting video from your PC to PPC
I'm just starting to look into DVR... Here's a page that shows how to go from TiVo to MPEG2 using directshow graphedit ( i guess it is part of the Dirext X SDK)