I don't know of any device with a HD screen that small, you just can't fit enough pixels on something that small with current tech. Other than the screen a netbook would fit your other criteria.
EDIT: How about this one, has an 11" screen with 1366*768.
http://www.amazon.co.uk/dp/B002J9GH3O/r ... B002J9GH3O
Ah, just noticed the use in all conditions. That takes you into the ultra tough laptops which don't come with HD screens. Also bleeding expensive!
Canon EOS 50D/EF-S 18-55mm IS/EF-S 55250mm IS/EF 50mm F1.8 II /Lowepro AW Slingshot 200/ Digital Ixus 860 IS
PC>Q6700/MSI P45 Zilent/6GB 800mhz DDR2/2x 4870 1GB/Samsung Spinpoint F1 500GB/Maxtor 200GB+80GB