If you do decide to go down the generator or inverter route be sure to get a pure sinewave one.
I've just bought one of these...
http://ww1.honda.co.uk/power/generat...tml?code=EU20i
It runs three laser projectors, a 1.5watt RGB, 2 x Green 1 watters, all the computer gear and touch screens etc. It has intelligent throttle and doesn't even break a sweat when running the above.
If you decide to go down the inverter route and are thinking of running it from your car battery be aware that you'll need to run the engine otherwise you could soon end up with a flat battery and be unable to start the car at the end of your gig. This is one of the reasons I decided on the generator.
Cheers
Jem