There is a AMD64 NEWSGROUP, and I read it everyday.
Do a search on google groups for more details.

What is the name of that newsgroup?
A Google on several obvious keywords only
came up with a debian topic.

And assuming the OP will have the same luck:

1. Does an Athlon64 motherboard require special
video cards etc or can it just take standard cards?

Nothing special. You can run AGP or PCI cards
today, and PCI-Express in the near future.

2. Is there an AMD64 version of Windows XP?

Only an aging public beta and a more recent
NDA-bound private beta. There's supposed to be a
released (although OEM-only) product "real soon
now".

Make sure there will be 64-bit device drivers
for all the components in your planned system.
This issue will be a challenge for a while yet.

You are aware, I trust, that the existing
XP 32-bit editions run fine on AMD64. Do note
that MS plans no 32-to-64 upgrade product in
the near future. So if you need 64-bit, and
must have Windows, wait for WinXP64-x86.

3. Do I need special software to run on
that 64-bit Windows or will standard
32 apps run just fine?

That was the whole point of AMD64 (vs. IA-64),
and it's the goal of Windows64 for AMD64/EM64T
that 32-bit binaries run flawlessly and with
no performance penalty. Actual Windows results
remain to be seen.


--
Regards, Bob Niland
http://www.access-one.com/rjn email4rjn AT yahoo DOT com
NOT speaking for any employer, client or Internet Service Provider.