Converting to USB 3.0
Now that I have a new PC with about half-dozen USB 2.0 ports how do I convert them so that I can use faster USB 3.0 when readily available?
As the others have mentioned, you'll have to add a PCIe adapter card with USB 3.0 ports in order to get the faster speeds. Your existing USB 2.0 ports can't be upgraded - although they look similar in appearance USB 3.0 ports are physically different and have more connectors.
I assume 3.0 devices will be downward compatible to 2.0 -- right?
Yes, you can connect a USB 3.0 device to a USB 2.0 port using a USB 2.0 cable and it will function at the slower speed. You'll get a warning pop-up from Windows stating that the device would run faster if you connected it to a USB 3.0 port.