o and, can I plug in USB2 devices into USB3 ports? That mobo only has 4 USB2 ports, :S
Yes. Existing USB 2.0 peripherals will continue to work with 3.0 ports and vice-versa. However, plugging in a USB 2.0 device into a 3.0 host will only be able to achieve the maximum speed and power allowed by the 2.0 standard. In other words, the speed and power allowed will be limited by the slowest standard connected.