yep it is the old gasket. You definatly need a new one (is it worth the risk when a new one only costs £5?) but you should ALSO buy replacement:
Studs and bolts. the studs are stretch studs, and will snap if you torque them up to the correct ammount. The nuts are oval, rather than round, not sure if these are ok with just new studs. Cost me £27

and much effort to remove 3 snapped studs.
You *need* a new plastic sleeve thing. Small peice of plastic that goes over one of the studs (right most) you need for aligning the manifold, only costs 50p........
AND last, there is a gasket between the manifold and the downpipe. On mine I thought it was part of the downpipe, however its recommended to replace this. I didnt, no idea how much it costs, but mine did leak slightly.