The relevant thing about my upgrade is that my U820 has an Intel Atom Z530 and is running Windows 7 which is exactly what the Nokia Booklet has. Oh dear. Nokia went for storage rather than speed (and probably used a 1.8 inch drive to leave more room for batteries) but at the price they have announced they should have put a fast 16GB SSD in there for the OS and a 160GB drive for the storage. Update: The drive is a 120GB SATA model.
The 16-cell battery (probably 4 serial, 4 parallel giving 14.8V) has a capacity of 3840mah (source: Slashgear) giving 56wh. 12 hours battery life is correct (radios off, screen brightness low) as we often see Menlow-based products averaging under 5w when in these very low-power states. Expect more than 8hr of hard browser-based ‘on-net’ time.