It's very difficult to believe someone when so many people say he did it. That said, when you've passed as many drug tests as he has, it's hard to say he has too.
Honestly, I'm not seeing any sufficient evidence to say that he did use PED's other then "He said, she said" statements. So until then, I'm not going to call him guilty.
I'm also on the boat that says that some things are better left alone. An amazing story about a guy with one nut winning the Tour de France 7 straight times is one of them.