Excellent article (and spreadsheet)to get the discusssion started

A real firestarter is when you start to look at standby power (a completely unneccessary expediture)

have you seen these?

http://www.treehugger.com/files/2005/12/smart_power_str.php

At my placeof work when you account for vacation time, stat holidays and average sick leave during a years means the average workstation / cubicle is in standby mode over 7200 hours per year

You can get get a device like this:

http://www.theresourcestore.ca/proddetail.php?prod=Kill-A-Watt-Meter

in orde to accurately measure your stanby usage at an a sample workstation and then multipy out from there based on the actual employees/workstations

Also be sure to factor into the caost of payback on the usb power strip devices that you buy a power bar/surge protector anyways