cavingjan is somewhat right.
What I gather you are tring to get a computer running to a hub... to another hub... and then to another computer. Em I guessing right?
If one of the hubs has a uplink port it is not nessisary to have a xover cable. But if neither one of the hubs have a uplink port, you must use a Xover cable between the two hubs.
Otherwise the "switching" that the hub does internaly will be wrong when it gets to the other computer.
Good Luck
Wolfie