Since I have been watcihng football seriously since only the last ten years I don't think I could do justice to an All-time XI.
However I would attempt to build a squad of 22 on the basis of what I have read, the clips I have seen and my own whims and fancies(and the fact that Man Utd sort of flows through my blood

)
Schmeichel
Banks
Maldini
Baresi
Bobby Moore
Beckenbauer
Stam
Bryan Robson
Cruyff
Platini
Maradona
Pele
Ronaldinho
George Best
Ryan Giggs(he is my favourite so can't leave him out)
Bobby Charlton
Duncan Edwards
Ole Gunnar Solskjaer(solely because I am a Man Utd fan and I haven't seen a better player,finsher and man combined in a football player)
Marco van Basten
Zidane
Le Tessier
Eric Cantona
So that twenty-two.
There are lots of players I missed out whom I like to watch and there is still a bais towards players whom I have watched rather than their reputation which is the reason for Ronaldinho rather than Garrincha making my team.
And I guess the squad is a bit weak on the defensive side and probably has quite a few players who haven't made it to the World Cup.
Ofcourse the odd selection would be that of Duncan Edwards who died in the crash of 1958 but that is basically because I am a Man UTd fan and his reptation at such a young age, there were others too on the plane who might have done really well but we will never know.
And yeah there still a lot of great players I have left out whom I would have picked on another day.