The Prescott 478-pin "E" CPU and the Prescott LGA775 "E" have different temperature profiles.
Apparently, the socket LGA775 design creates less electrical resistance, and so generates less heat, making it more "over-clockable" -- provided it is stable at low temps.
For my system, I had bought the mobo -- an ASUS P4P800 "standard" with ICH5 RAID, NIC, audio -- around December '03 -- just hanging onto it until I could complete an assessment as to what other components to choose. That i865PE board had some incarnations of "E" and "Deluxe" -- still pretty popular. So I had to stick with Northwood options. As far as I can tell with the mobo purchase, the only thing I missed was the Promise Tech Raid controller added into the mix. My BIOS upgrade has a file date of October or November '04.
I think in the '04 "Dream Machine" by Maximum PC magazine, they used a 3.4E and pushed it to around 3.97 on a PCI-X ASUS P5AD2 mobo -- using air-cooling and a ThermalTake HSF.
A friend sent me the 12-month graph of statistics comparing Intel and AMD stock growth. That is, the value of the stock increased by x1 percent in month 1, x2 in month 2 etc. AMD's increase in stock value was approximately double that of Intel during the last two months, reflecting expectations of expanded market share with the new Athlon 64 FX-55. But this is still just a "short-run" snapshot, and you would have to confirm the release-date of Intel's 3.8EE CPU -- which is likely to be the last in the P4-PRescott line. Were the benchmark comparisons between the "lastest" AMD and "Latest" Intel inclusive of the latest release?
They'll try and trump AMD -- and with Intel's resources, I'd look into the next year for something new.
If you just finished building a Northwood-based system and especially after buying, trying, experimenting, reconfiguring, tweaking and improving it over several months time as I did, the short-run market developments are no reason to dump it and go find the newest. Nor is it reason to change your plans concerning next year's build, (unless you can afford to build two, three or more annually or once monthly), but keep your eye open for innovations and developments which may "shift" your plans this way or that way.