This PSU is a better brand with higher power output on the +12v rail;http://www.newegg.com/Product/Product.aspx?Item=N82E16817371030
After the promo code and shipping it is also $17 cheaper.
For the card I'd get a single GTX 470. For 2560x1600 it is slightly faster than SLIed GTS 450s, you'll still have a slot free for an upgrade later and you wont have to deal with any SLI scaling/compatibility issues. http://www.techpowerup.com/reviews/NVIDIA/GeForce_GTS_450_SLI/1.html
In general it is best to start off with a single card and leave SLI or crossfire for an upgrade option when the time comes.
This one is $280 after rebate and comes with three free(and actually good) games;http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.455049