The 955 is the best bang for the buck. Forget the 1055t, I had one and there's nothing special about it. A C3 black edition 955 will be more than you need. Most overclock to 3.8-4ghz with a slight voltage bump even on the stock cooler.
GTX460's rock, make sure you get a 1gb.
GTX460's rock, make sure you get a 1gb.