I can't say anything about mixing G and Super-G. Until now I thought Super-G was a ski race.
But you should be able to run a switch off the access point if it has a CAT5 port available. Either that or get a wireless bridge. My wife's PC upstairs is connected to a wireless bridge. It's Cat5 to the PCs and wireless to my wireless router. You can hang a hub off a bridge and connect multiple PCs to it.