Can't you afford to buy a real laptop if power conservation is important to you? It is important to me, so I spent oodles of money and got a laptop that lasts 5 hours (and 10 hours with a 2nd battery), plus I have a digital tablet for taking notes (that lasts for about 20 days and will take 50 pages of notes). I back it all up to a Microdrive, so I can lose the laptop while traveling and still have all my data. Never really need inseat power unless I want to watch DVD movies, as the batteries last long enough. But I have noticed that the cheap laptops, even Dell, have mediocre batteries and poor power management (some don't even use a Mobile cpu, to save money).

As for in-seat power, more than half of CX planes have it functioning, which is about the same ratio as SQ (where it seems to be off quite often) and BA. CX got distracted with Tenzing and fell behind (they would be far ahead if that technology had panned out). The only reliable inseat power is by LH (who supply 3-prong AC, rather ironically). All the other Empower-ish systems seem to have reliability problems.