i think the Shuttles are very modestly rated, those numbers might represent sustained wattage rather than peak wattage. a dual core and a 1900 "might work." I'll let sum1 with experience give you a better answer.
Any other ideas? I don't think a dual core processor was made for socket 478... Right now I'm looking at a 3.0 ghz northwood. I figure that I need the 800 mhz fsb and that the cpu speed doesn't have to be the highest out there.