I always found that 26" wheels are fine on pavement with the right rims and tires (like 1.5" wide/80+ psi).
But obviously if it is full-on speed you want, you really need 700x23c with a minimum of 120 psi on nice light wheels. It's worth spending the money for good wheels, even at the expense of everything else. Rolling weight makes a much bigger difference than say the weight of the frame.
