Federer will win all 4 slams in 2007!
Federer is an intelligent player. He sizes up his opponents and different surfaces whenever he plays. It has been a lot easier for him to learn how to beat the other players than Rafa...most especially on clay where the Spaniard reigns supreme. However, I believe Federer had enough sizing up in Roland Garros, reaching the finals in 2006. He might just get it this year.
Thus...
Australian Open.....got it....check
Roland Garros....probably (hoping!)
Wimbledon....no doubt!....check
U.S. Open....no doubt....check
And it's not like Federer is injury prone like the other players....No withdrawals...No retirements...