Normally Intel's Xeon Nocona processors should be available on Monday, August 2. The Nocona processors feature Intel's new 64-bit technology, EM64T (Extended Memory 64 Technology). Also available on Monday is the new Lindenhurst chipset for servers.
New Pentium 4 Prescott processors with EM64T can also be expected on Monday, though these will not initially be available for normal users.
Information about the Pentium 4 Prescotts with EM64T was found at one of HP's Product pages. Probably they will be delivered this processor to some OEM's, like HP. X-bit Labs wrote this some time ago:
Intel said it would ship Prescott processors with 64-bit capability for 1P applications only to system integrators requesting such microprocessors for their servers and workstations. Although all Prescott CPUs, including Intel Pentium 4 and Celeron, are 64-bit from micro-architectural standpoint, processors supplying for retail channels as well as for typical desktops will have their 64-bit capability disabled.
However, some sources doubt that it will be absolutely impossible for end-users and hardware enthusiasts to get Intel’s 64-bit Pentium 4 chips. They suggest that there will be some of such microprocessors supplied as OEM parts and reaching the channel.
Prices are unavailable yet, but probably these won't be more expensive than the regular Pentium 4 models.