Okay, i have to comment on this Messi debate
I'm a lifelong united fan, just so you know my background. However...
I believe that Messi is just a tad better than Ronaldo. Would i swap Ronaldo for Messi? Of course not, Ronaldo is a united hero, his scoring rate is immense and he's a truly gritty player. But Messi controls a team of egos and outshines them all at the age of 20.
He consistently outperforms Ronaldinho, Eto'o and Henry, and it doesn't seem to matter who's around him. If Rijkaard can only pic one forward player, he pics Messi, then two others. As for Cristiano Ronaldo, he gets much better when coupled with Wayne Rooney, his goals drop off without Rooney. I'm not even sure who's better between Rooney and Ronaldo, let alone Messi.
Ronaldo obliterates league opposition, he's the most direct player there is, his pace, both footed-ness and aerial presence means he's unstoppable to most teams. However, in big games, he can be marginalised if teams focus on taking him away (See: Milan 07). Wayne Rooney, however, is just as effective against all opposition in all circumstances. (See: Milan 07) In our really big games, i look too Rooney first if i'm honest. And this is how i see Messi. World-class but ultra-reliable.
There really is so little between it that it's almost irrelevant, but even if Messi is only as good as Ronaldo, the fact that he's only 20 still clinches it for him.
But i wouldn't swap Rooney or Ronaldo for him, no chance. Messi is Barcelona these days, and the two R's are Manchester United.