but how hard would it be to upgrade my MB to a crossfire MB or is it not even worth it cause to me it seems like ATI is winning highest FPS in every bechmark now days plus with AA and AF on.
It will not be very difficult to upgrade since you already have the other components for eVGA board. You will just need to remove the parts on your old board and put it on CrossFire board. There may be a few complications thought as Windows is very sketchy with motherboard upgrades, so if you do decide to upgrade the motherboard, back up your files and prepare to reinstall Windows if needed.
I'm not really sure about your second statement as you states its not worth upgrade because ATI is winning.
What card do you have right now? Also you should consider the fact that the most your eyes can perceive is 30fps, so anything higher will not make a difference.