As to the power supply connection, why not some splitter since the USB 3.0 power requirements are very very tame.
I have a Gateway SX 2801-07e , running WIN 7 64bit, that is equipped with USB 1.1. I would like to add a USB 2.0 card. the tower is a "mini" so I need a 3 1/2 inch card with the small foot connector. There isn't an available power supply to go to 3.0. Any suggestions on where to find the card that fits?