Hello? Does anyone here have a clue?
Pentium M DOES NOT SUPPORT EM64T. THE P-M IN YOUR 700M NOW WILL NEVER SUPPORT 64-BIT!!! EVER!!!!
The first P-M processor scheduled to *maybe* have EM64T in it will be Yonah, due sometime in 2H 2006. It is theoretically possible that in 2H 2006 maybe Dell will release a BIOS which supports Yonah in 700m and then you will get 64-bit support, but it's unlikely since Yonah will at least start at the 533mhz FSB and most likely will have a 800mhz FSB. It is unlikely that there will be a 400mhz FSB Yonah. Plus Intel hasn't even confirmed yet that Yonah actually will have EM64T, since P-M is still a mobile chip and Intel isn't planning to officially introduce P-M to the desktop for some time still. They might even wait until the P-M after Yonah to get EM64T into it.
There's a 99.999999999999999999999% chance that the reason Win64 is listed on the Dell website is simply because Dell sells some PCs, desktop P4 PCs, which support EM64T (any P4 with the Prescott core supports it) and they didn't feel a pathological need to make the option vanish when you select a system which doesn't have an EM64T capable CPU. Yes, it would cut down on the n00bs calling Dell and demanding to know why they can't install Win64 on their 700m's, but I don't think Dell cares too much.