I have been wondering what size inverter I might need. I can only find a 100 0r 175 watt. I cant rewire the company truck so it has to run from the cig lighter port.

Will either one be enought to run a tv and or a laptop?

You should be able to find up to a 300 watt that will not require hard-wiring. Look at the back of the appliance, and that will tell you how much power you need to run it.

You can go up to a 400 watt inverter and still use the lighter plug.

http://donrowe.com/inverters/xpower_400_micro.html

Laptop yes TV no, unless maybe it's an LCD

Most cigarette lighters are 20 amp, 20 amps X 12 volts = 240 Watts

Nowhere near what you need to run most TV's

Laptop... probably.

A 400 watt inverter plugged into a 12v power outlet will run a 13 inch tv/dvd combo.

No need to, I have a 400 watt inverter, and 2500 watt in my truck, and the 400 has run without any problems in the lighter plug, with items rated above 150 watt continuous. It is a 400 watt inverter and most would use it for tv's and laptops etc, not big watt items which has worked fine for me for many years.Thanks for the observation.

Depends on the company too.

Swift:
* 800 Watt Max (Proof of medical necessity required)
* YOU have to purchase the wiring for it, and it becomes the companies.
* 300 Watt Max for general use is all they allow.

US Xpress:
*1700 Watt max (I only got a 1200 as I don't have need for a 1700)
*They hard wire it right off the bat.
*I do not know if I have to supply the cable.