The Pentium M is a good idea, and depending the the competetion it may very well be my next purchase. It's just got a couple of bumps that need to be smoothed over for me to actually consider it in a desktop. First, DDR2 I am clearly avoiding at this point. I also don't like the "adapter" thing Asus has rigged up for this to be used in a desktop motherboard. If they make it an actual chip that fits in universal sockets I think they'd find much more success.
I have a Pentium M in a laptop, works well, and I did my homework before buying it. But desktops and laptops are apples and oranges and I can't really say if I like the P-M over a AMD Venice.
edit - AMD plans to be in control of a third of the market by next year, and has 50% in the next half decade or so planned I believe