You can do better than that PSU. I would never even consider such a cheap unit. If you get a cheap MB, CD drive, whatever.. you end up having to replace it. You get a cheap psu and you may end up replacing it and everything it is connected to. Get one with a good warranty and support.
Corsair, PC PnC, OCZ, Antec to name a few.
As for the 260, they are all the same really. Those you linked are identical cards. XFX has a double lifetime warranty and evga has a step up program (in some countries). Generalyl get the cheapest one, or whichever comes with the better games.