Hi Order
To your needs I would look into a UMPC - less then 1 kilo weight, 7” screen, full windows computer inside (no speed demon, but gets you any normal work done) and can ready any eBook/digital format you want.
Not cheap, but can replace your laptop on the road and at the office or home if you want.
Lots of information about them (and also tabletpc’s):
http://www.gottabemobile.com
Bets regards,