Swapping wireless card to N

[Black Falcon 921]

I have a dv5 1235dx. I just purchased the laptop a few days ago and I was wondering if I could switch out the G card inside to a N. I know that it can be done but I only have two antenna wires and the N cards have three spots for antennas. I was seeing if it would be a problem if I only hooked the two wires up or if it would even work with just two antennas instead of three?