Well sorry but you cant have Rodwell. We'll never sell him. Just like you can't have Rooney as we'd never sell him either 
Yeah it's all very well to say 'Oh he'll fit in nicely at United etc.', but Everton do need to agree to sell him, and a fair fee worked out.
Somewhere I was reading the other day was saying if he is your most valuable asset, along with the fact that maybe he doesn't make your top XI if everyone is fit, maybe you could sell for a decent fee and then bring in a few quality players to bolster the squad.
As an aside, I do think Ashley Young will end up at United next season though. His contract only has a year to go, he wants to win things and is becoming an England regular. Sounds like an ideal Ferguson signing.