SInce you are using a 95W CPU - you should be OK with the 400W PSU. -- as for which one those are all pretty much the same so whichever is the best price would probably be a good choice --- though for the extra $15 I'd probably go with the Sapphire Vapor-x edition for the better cooling.
More important than the 20A 20A is the combined rating of 32A (384W) -- so it should be fine for the 95W X4 and the 5770 and the rest of your system.
Either of the 2 is fine main difference is the full shroud will run a bit hotter itself but keep case temp a bit lower (the shroud limits airflow around the card itself but vents out the back of the case) while the open model will run a bit cooler itself but raise the case temp a couple degrees (airflow is better around the card but warm air is released inside the case). So which is better depends on the system it is used in. --- For the price though the Vapor-x sapphire linked earlier is what I would go with. (it has a liguid inside the heatsink that turns to gas when heated and back to liquid when cooled so removes the heat better)
But in the long run they are all decent and will work (the 5770 does not use a lot of power so heat dissipation isn't really a problem with them no matter which one you go with.