This article comes from Australia, but except for the mailing cost appears to apply to the US as well.
The good news is that 64 bit Vista is not for the faint-hearted. If you want a lot of frustration, order up a copy. Otherwise stick with the 32- bit version.
On a another subject, but one that didn't deserve it's own post, have you seen the Vista "Wow" campaign? The consensus seems to be that the ads are pretty lame and unbelievable. I saw a great tag-line based on it the other day:
Vista: we put the "ow" in "Wow".