Check the PSU Guide sticky. Ste just redid it recently. Lots of good info.
Rosewill are decent and work for cheap builds (like this one). You would want a better name PSU in a power build, though.
For two monitors you will need a card with two or more outputs. You have a PCI-E x16 slot, so you could use any recent card for that. You could pick up a 4650 for $50 or so, or a 4670 for $70. Either would be a step up graphically plus give you your outputs. I don't know if any other GFX cards work with Hybrid Crossfire besides the two from the 3xxx line and the two from the 2xxx line.