I know that exists a retrocompatiblity, but those PSOne games I've own, were bought before PS Vita being released.
Possible Duplicate: Does the Vita's backwards compatibility with PSP games extend to PS1 games? Amazon's description of the PS Vita states: Vita can play PSP titles, minis, PS one ...
I am aware that some games (like the early Final Fantasy titles, Disgaea) which are on PSP (more appropriately, PSN) are later versions with a small amount of extra content. Normally it is fairly ...