|"Cloned an HDD on one pc,and put it into another"|
That was your first mistake.
XP installed in one hardware environment cannot ( generally) boot up in a different hardware environment. At a minimum you will need to perform a repair install in the new PC and you will need your XP Install CD in order to do this. You may encounter other difficulties with driver incompatibilities and drive recognition particularly if the original drive was IDE and the new one is SATA.
Goin' Fishin' (Some day)