I think I have found the perfect 24/7 weather computer. I bought a Fit-PC2 from Compulab to have as my weather station computer and at the same time it works as a media server in my house. It's not bigger then 12 by 12 cm, it's fanless (totally quite) and the total power comsumption on full load is 8 watt!!!! That means its really cheap to have running 24/7 It has both ethernet and wireless connection. 6 USB, IR, SD card reader and works great with Windows XP operating system. 1.3 Mhz Intel Atom, 1 Gb Internal memory and a 250Gb 2,5" disk in it. Could be fitted with a SSD if needed.
I might even have an extra Fit-PC2 up for grabs if anyone is intrested.