I am strongly leaning towards upgrading to a GTX 670 and an i5-3570k. I would most definitely overclock but have no experience doing so. It would be great if I could get a list of every part I would have to replace to be compatible with the new cpu and gpu including a good cpu fan and also recommendations of different processors and video cards I could go with. I also want to know if a 128gb ssd would be worth the money with a build like this. I am most interested in continuing to use the computer on games such as Guild Wars 2 and Battlefield 3.
I use biostar boards, and they will overclock. I recommend for some folks with little build experience. Some asus and asrock boards won't post with certain brands of ram; I've never had this problem with biostar.