Something like that was what I was recommending Steve to use in his project. You save on all the voltage conversions.

Two major problems with this solution (i've investigated this solution)

1) It weighs a HUGE amount! 8.5 KG of lead-acid battery pack!
2) Running 12V through an inverter to 110v and then through an ad/dc adaptor is terribly inefficient. Not to mention 110v being dangerous.

I would recommend it for expeditions but not for general mobile computing.

More efficient is the 25W Sunlinq with a TabletKiosk/Tekkeon MP3400 batttery pack (1.5KG for 65W/hr - good for 5 hours UMPC work. Charges in 5 hours FULL sun.)
I'll be using this setup with a smaller 6ah lead acid battery for backup and buffer storage.

Steve

I work at Office Depot, and this school season, we got in a backpack with a solar panel on the back. It can charge most small portable devices including phones, PDA and MP3 players. It's a really cool concept, and only costs $60. There's even a charger included so you can have power stored on cloudy days.

$60 is a good price if its a good specification.