Correction, Nadal was present but got beaten in the semi final by Soderling, who Roger then beat comfortably in the final. I accept though that had Nadal got past Soderling he would probably have beaten Roger in the final given his dominance on clay. One other point, yes Roger only has one French open title and 7 Wimbledons, but he has also won the US Open 5 times and the Australian open 4 times, so to say most of his titles have come on grass is simply wrong, given that over 50% have come on other surfaces. Added to which he has won the world tour finals 6 times to prove that he is also great on hard courts.
Perhaps Rafa would have won more titles and would be close to surpassing Roger's record had he avoided injuries but we will never know. In my view, Roger and Rafa are far above the rest. Djokovic may come into the equation in years to come but he has only had 18 months of dominance, where Roger had about 6 years and Rafa had about 4 years. If Novak can maintain his current form and continue winning 2/3 slams a year like Roger did for so long, then he can be considered in the same bracket.
Murray is a great player, the fourth best in the world (I know he's 3rd in the rankings, but that's only because Rafa has been out injured for so long, there can be no doubt that Rafa is the better player) and miles ahead of the fifth best. I believe he will probably win at least 3/4 more slams during the rest of his career. That said, I still believe he is some way off the top three and is unlikely to ever rack up the kind of numbers that they have in their careers to date.