I think KOTTS has it pretty close. We may feel faster on a lighter bike. I know I am faster on my road bike compared to my mountain or comfort bike, but they are different bikes for different types of riding. I could probably ride a carbon fibre Jamis and not notice any difference other than I might feel faster. I weigh too much to make a noticable difference. When I am at 5% body fat, then maybe worry about the weight of the bike and components. So, in other words I am not planning on worrying about the weight of the bike or the weight of the components.
__________________
2007 Jamis Ventura Comp
2006 Jamis Explorer 2.0
2000 Specialized Hardrock (bought used)
Swim, Bike, Run and sounds like fun