Scwartzgraf's got a good point - why is your Wiz on a barded warhorse? Is he going to be running with the IC Knights? If so, why? What lores are you thinking about using, too?
I think that in a 500-point game, the Empire can actually field a strong (for the points size) magical presence. But the trick there is the Rod of Power, not the Wizards Staff. So look into that. Otherwise, your list has good potential. Get that Wiz off his horse, though.
Oh, I just noticed that your Knights have Full Command. This is probably a bad idea. I would lose the banner - it's probably just going to give away victory points.
-Visu