I came across an interesting article at biketechreview regarding how bicycle wheel design relates to performance. The long and short of it is:

Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into:

1) 60% rider drag
2) 12% rolling resistance
3) 8% frame drag
4) 8% wheel drag
5) 8% bike/rider inertia.
6) .5% wheel inertia forces
~3% attributed to drivetrain and component flexing

I'm by no means suggesting this is gospel, but I find it to be an interesting perspective on what really matters. when bike and rider (sans wheels) are treated as one even a few pounds of weight make a pretty miniscule difference....until you're climbing.