USB 1.1 and 2.0 both use the same connectors, so there shouldn't be any issue with connecting your case wires to a USB 2.0 header on your motherboard.
USB 3.0 uses different connectors, though.
I did connect the case connectors to the motherboard, and the m/b does support USB 2.0. But when I plug something into the case connectors, I get the message, "This device could perform faster."
I know it's a minor issue, but I wanted to be able to use the case connectors. It appears there is some minor circuitry inside the case which limits it to USB 1.1. I am considering trying to salvage the circuits and connectors from a small external USB 2.0 port, and installing it into the case. I though perhaps there were upgrades to the case from Antec.
Probably it isn't worth the effort to try to replace it with salvaged parts.