better CPU cooling = better chances to a higher CPU overclock
better North Bridge cooling = better chances to a higher FSB
The key word here is "chance" - you had it right in your title. OCing depends heavily on your mobo quality, your RAM (with Corsair things should be OK
), and if there's a PCI / AGP lock (in case of FSB OCing).
But if there's the potential, watercooling will allow you to exploit it.