Be careful with the wattage limits. I have a 100 watt whistler. It's great, but won't power my laptop. The 100 watts is split between 2 plugs, so it's really a 50 watt X 2. You can power a couple of things with this, but it takes a hardcore 70-90 watts to run a laptop, so you'll want at least 200 watts to cover it without the circuit shutting down. Also never run it without the engine running.
I have to echo what jonnyGURU said. Get one with a fan. Walmart actually has a couple of them for around $40. A coworker bought one a few years ago 350-400watt. It does the job of powering his laptop and keeps cool with the fan. My little inverter heats up when I really use it.