Not really. It would be hardly note worthy. Should just come of a few points more, and is not worth the extra money. You should be just fine with 3.0 Ghz.
Yeah, the 6** chips are EMT64 chips, however the older 5** are faster clock for clock in most enviroments
The difference in 200MHz, especially on the Netburst architecture, is incredibly insignificant, and a 3GHz core can easily be overclocked beyond 3.2GHz