The Feared "Incompatible Security"

I've looked through other problems like this, but none of them can help me.

I had been using my Macbook for a few months, and two days ago the internet went screwy on us. After a Comcast guy fixed everything, the computers running Windows can access the WiFi network, but my Macbook cannot. I can't even figure out what kind of pass word it uses, WEP, WPA, WPA2 etc. I tried putting a $ in front of the password, and that didn't work. I'm utterly stuck here :/

What are the windows boxes set for?

I can't tell. I don't know where to even start looking for that.