I think you underestimte how strong Messi is. Yes he is no Emile Hskey, but he is still so hard to knock of the ball because of his low centre of gravity and his upper body strength. I remember watching the el clasico and even some of Madrid's more powerful players (the likes of Pepe and Carvalho) could not get the ball off him.
United fans in general underate Messi. A leftover from the Ronaldo vs Messi debates from when cristiano played for us. The same can be in general said for our rivals tendency to criticise Ronaldo.
Messi will not be one who will win Barca the game if they go on to win it, you'll be so concentrated on him that you'll end up conceding to someone else nearby :/
True, but then Pepe and Carvalho weren't helped by the fact that every time they fouled him the Barca players all started asking for a booking. If Messi played in the PL, he would be the best player here by quite some way, much like Ronaldo was. But I agree with Tunns that he wouldn't find it as easy as he does in La Liga. The same way Ronaldo has been much more prolific since joining Madrid, I think Messi is more prolific for Barca than he would be at a PL club. Part of that is of course the level of service that Barca give him, but part of it is also the fact that the Spanish game makes it much easier for Messi to thrive - whilst clubs still try to foul him it is very rare that any club will set up their tactics specifically to stop him. If you compare that to Ronaldo's last season in England, a whole lot of PL clubs set out their stall specifically to deal with him, which made him around half as prolific as he has been in Spain. If Messi came to the PL, I think clubs like Blackburn, Stoke and Villa would be better able to deal with him than clubs like Almeira, Osasuna and Sociedad have done in Spain. He'd still give them a tough time and would still score goals, but I doubt he'd rout them as easily as he has done many of the Spanish clubs.