Hypersmurf
Moderatarrrrh...
That 5-feet step becomes part of your total move. If your base speed is 30 feet and you use Spring Attack on a designated opponent, you move 5 feet and attack, and then you have the remaining 25 feet of movement to be used.
There's a difference between moving 5' as part of normal movement - which does provoke AoOs from everyone except the target of your Spring Attack - and a 5' step, which can only be taken if you move no other actual distance in the round.
-Hyp.