9800 GTX is a poor choice, at least get the newer model called the GTS 250. I still would recommend you go with the ATI 5750, which has DX 11, the same performance and uses less power. For around $25 more than that 9800 you can get a 5770 which is around 50% faster (equivalent to a GTX 260) and has dx11.
That seagate 1.5TB is likely to be a 7200.11 model which has had firmware problems. The Samsung F3 1TB is newer, faster and more reliable for less money.