the e is just an enhancement. i mean cat6e drafts exist, and cat7e drafts exist.
i am not an expert, but i know for sure that cat6 is something all together different than cat5e.
i did a search for CAT 5 info on hotbot, and found a nice place... but that was a while ago. linksys would not have all that CAT stuff, meaning unofficial stuffs...
but i do highly recommend the linksys FAQ pages.