L'équipe, a prominent French sports newspaper, published an article about the Tour de France of 99 in wich they say they have prove of Lance Armstrong having used epo. You can find an article about this on the webpage of L'équipe.
www.lequipe.fr
I'm sorry that i haven't found an English source but you try to do a search for that with the key words 'Lance Armstrong' and 'epo' or 'doping'. It's almost impossible to get a good source but it was all over the news over here so i think it's safe to assume it was all over the news about everywhere.
So did he or did he not ?
As to what i think. I think he did use some form of doping but on the other hand i also think that most, if not all, of the cyclist in the peloton use something so it equals out.