I've been reading a bit into it and people have said some GFX cards need more amps on the 12v rail. I'm looking into an HD 6570 or 6670, could any of you guys help me out with how many amps would be sufficient?
Not many. The 6570 and 6670 are both low end cards that don't need a lot of power. Any QUALITY 300-350W PSU should have no problem. In your case its more important to get QUALITY rather then amps/wattage.