1) PSU is good enough for the two 5970's... it is a very good PSU. I'm running it myself.
2) I would recommend against the VRaptor and the Xeno Network card. They are not worth the money for little or no performance increase... IMO. I would just go with the on-board 10/100/1000 LAN and I would recommend the Samsung Spinpoint F3 500GB hard drive, which pretty much matches the performance of the VRaptor for 1/4 the price.