If you take away the 2 extra votes each state gets for their Senate delegation, and go purely on a representation by population basis, Bush’s margin becomes even slimmer:
Bush: 224 :: 286 – 62 (31 states x 2 “extra” votes apiece)
Kerry: 212 :: 252 – 40 (19 states and “DC” x 2 “extra” votes apiece)
The real margin of victory is 6 electoral votes, or Iowa (5) and New Mexico (3) (for example). A mandate? I don’t think so.