The Antec PSU is a great one. It would even handle the build if you threw in a fairly meaty GPU (like up to the HD 68xx cards).
As for it you need a discrete card, it really depends on what you're doing. If you're just using it to watch videos, onboard will be fine, especially with Sandy Bridge's integrated graphics. If you're trying to play some games, I'd porbably throw in a discrete card. If you do end up getting a discrete card, I'd get a P67 board. The main benefit of the H67 is the integrated graphics, which you wouldn't be using.