Upgrading Video Card. Will it fit?

Hey guys, I am looking to upgrade my computer for some gaming! Now I’ve done a little digging around and I just have a few questions before I make a purchase. (Sorry, I am new to this!) I have these 3 video cards picked out. a) http://ping.fm/VCwiN b) http://ping.fm/YqYLZ c) http://ping.fm/NGQtF I looked up reviews [...] http://bit.ly/patQTS