Everything looks good but the GPU the GTX 260 good but you can get the same thing for cheaper if you get an ATI Radeon 4870.
http://www.newegg.com/Product/Produc...82E16814150394 Now as for you motherboard I would get this
http://www.newegg.com/Product/Produc...82E16813128358. By the way you can get a better system if you go with AMD and it will save you money.
http://www.newegg.com/Product/Produc...82E16819103471
http://www.newegg.com/Product/Produc...82E16813128387
everything else you have will work with it you can use the extra money to get a ATI Radeon 4890 for $50 extra its as good as a GTX 275.
Do what you think is right