I also like the look & spec of the XPS M1330. I contacted Dell this morning to ask if it is actually fanless : after quite some time - nobody seemed to know - they replied that as far as they know it has at least one fan but will be "very quiet". I also see from the Dell forum that although you can order one, they will not ship in Europe before the end of July and will likely not be available in any volume till after the summer.
So quite some questions still to be answered.
At present my #1 wish list silent notebook is this the latest version of the new Panasonic Y7 (can't post a link as this is my first post, but it's on the GeekStuff4U website). The issue for me is that it has max 2G RAM, whereas the M1330 will take 4G (& faster ram as well), which is what I would prefer (I run financial applications).
I'll make a decision in September...
I once longed for a fanless laptop, but one with a fan that stays off on low cpu usage is sufficient IMHO. My dell 9400 core 2 duo runs passive between 50-58 degrees with stock thermal paste. Of couse, if you apply a load without undervolting, all bets are off. But for general word processing /firefox, it could easily run passive. My guess would be that most notebook CPUs these days can run passive, but are limited by the paranoid fan controller (not an issue with my dell).
I can't help but imagine what companies could accomplish if they went all out increasing the heatsink size by about 50% and using fans with low startup voltages. Some of these tiny notebook fans are quiet at 2,500rpm, they would be inaudible at half that speed IMO, and provide enough cooling even under load when undervolted.