I could really use the advice of some fellow cyclists. Currently I have on my bike Campy Daytona. The parts left from the original group I bought when it was new, I think 2000, are rear derailer,brakes and ergo
shifters. I was thinking of updating my bike with new Campy but really do'nt know which one to pick. I want to be practical about the purchase but at the same time don't think I should make a sideways move in quality,(i.e. Centaur ), or would that even be an upgrade to what I'm presently using. Can anyone shed some light on my dilema?

Daytona became Centaur, so if you replaced everything w/ Centaur you'd essentially be staying at the same level of components. One thing to keep in mind is that the "multiple-shift with the thumb lever" option is now gone unless you get either the Record or the Chorus brifters. You can mix-and-match components -- i.e., Chorus brifters will work just fine with Centaur derailleurs, for instance.