Wheel Upgrade..

skooter Posts: 264
edited May 2013 in Road buying advice
I have read many times that a good upgrade is to change the wheels, so a question or two please.

The bike in mind is a Cannondale Bad Boy 2 fitted with Maddux rims.
So if I upgrade what would be an upgrade as I have no idea on wheels that would be better than the Maddux's fitted to the bike at the moment.
Dont want heavy wheels the lighter the better and good rims for the price/money.
Would £400 cover it or would I need to spend more or less? I would of course change over the brake disc's and cassette.