d00d, are you on cracks? K, check it out, that cable makes an ATX PS work with an AT board. All this guy wants to do is power the DRIVES with the second power supply, that's why I recommended at AT power supply, they can be had almost everywhere for free and most run without a motherboard attached.
Sure. In fact, his first post implied that they would not be connected together. While having them connected to a common power switch is handy, it's unnecessary and not worth the trouble IMO.