External antenna for b130?

Alright so I have an Inspiron B130 and I would like to get an external antenna for it. I have some time inbetween classes at my school which I like to spend in my car (I seem to get my best thinking done in there) but the standard Dell 1370 card that comes with this gets a very weak signal from the two closest routers from the car. However, I think theres hope because theres 1 bar on both of them. Ive heard this could be solved by getting something called a "pigtail" for the card which allows for an external antenna.

Unfortunately, I don't know a whole lot about laptops/wireless networking but I sure would appreciate some advice on this. I want to attempt to do this on the cheap.