Are the 12v going to have a duel with swords?
It does not matter about the dual 12v lines. Antec PSU's have dual 12v's and It means there are dual rails or something on those lines, which means 'better stability' but it doesn't really matter, make sure that the amount of amps on the 12v are good.
As a minimum, of would say 450 from a top company like OCZ, but idealy you want more than that.
OCZ, Antec, Thermaltake - great quality PSU's at reasonable prices, Enermax are the top ones. I would say OCZ was the top one, but can be pricey.
Cisco CCNA, Comptia A+, 1/3 through CCNP