Cannot connect to Wi-Fi (The Wi-Fi network "network name" requires a WPA2 password)

I have had my MacBook Pro for a couple of months (recent Windows convert and total Mac novice). I am running OS X 10.8.4. Our cable company recently upgraded our modem and cable box and I am no longer able to connect to the Internet over Wi-Fi. I can connect via Ethernet. Also, two windows laptops, two iPhones and an iPad are all connected via Wi-Fi so I believe the wireless signal is working and can be connected to. I can see the network but when I enter the password the login box shakes like an incorrect password was entered. This is the same password I use for the other devices and I have carefully entered it many times so it should work. I would appreciate any thoughts you might have.