I have a similar battery-based system, but it's a bit more portable and can usually be had a bit more cheaply:
Portable Car Jumper Battery I don't have this particular setup; just wanted to link an example. In a nutshell, get one of these car jumpers and either an inverter (90 Watt should be enough) or get one that has an inverter built-in. It will power your devices for a good long while, you can also use the inverter in your car cigarette lighter (mind you don't drain your car battery), and you can usually recharge this system from your car when the power is out for a long period.
I used a setup like this during Irene's aftermath to charge my cell phone and recharge my laptop battery as needed. It also has enough oomph to run a lamp with CFL bulb and a small fan.