March 31 was the first date Neowin.net posted that you were able to download a ISO of it if you had purchased a copy of WinXP Pro. You can also trade up, but you have to talk to Microsoft before a certian date, which is up and coming fast but I couldn't find the exact date.
I asked my distributor about WinXP 64 and he wasn't much help, I'll go ahead and do the e-support link that you posted but I would put more faith in it working if I heard it from a user rather than from Scanvec. In the past we have had problems with their software doing what they said it could, but guess what, we still use it.
First of all, Scanvec-Amiable have hardly even made Flexi a fully functioning Win32/NT compliant application. There's a hodge podge of all sorts of ill-designed code in there. If the app had been fully 32-bit and NT compatible we wouldn't have seen those hangups with Flexi 6.x dying on WinXP Pro setups. To contrast, an old version of Photoshop will run just fine on XP Pro.
With that in mind, please stay far far away from WinXP Pro x64 Edition.
At this point, the upgrade to that OS is a very hazardous undertaking. That's one reason why the upgrade is being offered by Microsoft for free. If you have a computer with a 64-bit capable Intel or AMD processor all you have to pay is the shipping charge for the disc. The downside is you lose your license to your previous 32-bit version of Windows.
Why is WinXP Pro x64 a very risky install? The biggest problem is device drivers. Sound cards, video cards, scanner drivers, graphics tablet drivers, other on board utilities, virus scanning software, firewall software and more will likely not work at all under this 64-bit version of Windows. Most of that stuff must be recompiled for 64-bit code. Some of the problems may be solved with fully NT-compliant 32-bit code.
Older applications will likely not work at all under WinXP Pro x64. There is no support for anything making any kind of 16-bit commands. A lot of older apps made to run "good enough" for Win95 still used 16-bit installers (often yielding that nice old Win 3.1 appearance).
At this point, the only people that should even bother at all with this new 64-bit version of Windows are enthusiast tinkerers who can afford to hose a computer system. I don't think I would even advise anyone buying a new computer system to have this OS installed due to the lack of supported hardware.
The best thing to do is wait for at least several months so developers can have time to get drivers updated and popular software applications patched. Many are working to accomodate the 64-bit thing, as well as even taking steps to get applications to work in multi-threaded form to harness power from the dual core CPUs that are now starting to hit the market.
Windows XP Professional x64 Edition provides a rich platform to integrate 64-bit applications and existing 32-bit applications using the Windows on Windows 64 (WOW64) x86 emulation layer, providing customers with the ability to move to 64-bit computing without having to sacrifice their existing investment in 32-bit software and Windows expertise.
In theory there should be no issues with running Flexi on XP x64 edition....