That will depend on what version of XP is on the disk and the speed of the OP's internet connection.
For the last time, it's not the disk that is the licence it's the code the OP got with his / her original XP(probably stuck on the side of his / her machine), as long as the disk is the same flavour of XP (i.e. an XP home disk for an XP home code) then there are no problems.