The 5670 will play TF2,CSS,Wow with no problem on max settings...What is GW2?(gears of war?)
You can find a 5670 for around $80.http://www.newegg.com/Product/Product.aspx?Item=N82E16814102869&cm_re=5670-_-14-102-869-_-Product
As for your PSU,i'm not sure about this, but i do think it is a quality one i think with all of it together it is near the max your PSU can handle.You should get some other opinions about your PSU it might work/it might not.
If you wanted to buy a new one i would suggest this one.http://www.newegg.com/Product/Product.aspx?Item=N82E16817151077