alsa and amd64 arch

[Jonathan Kaye <jdkaye10@yahoo.es>]

Hi all,
I already sent this message to debian.user but no response over there so I
thought I'd try here. 
I finally plucked up my courage and put in another hard disk and
installed 2.6.8-11-amd64-k8 which is running independently of my i386
installation. Loads of problems but perhaps the easiest is what do I do
to get my architecture into /etc/modutils/arch and/or /etc/modprobe.d/arch?
I can't install the alsa drivers because although alsa finds the correct
card and driver snd_via82xx, it whinges about not finding
the amd64 architecture as shown here:
Running update-modules...
Architecture-specific modutils configuration not found, using defaults
Loading driver...
Setting default volumes...
 
The contents of the /etc/modutils/arch is:
alpha  m68k.amiga  m68k.generic  mips.ip22     powerpc.generic  s390
i386   m68k.atari  m68k.mac      powerpc.apus  powerpc.pmac     s390x
The contenst of /etc/modprobe.d/arch is:
i386
but no amd64 listed in either. I've got the kernel-source headers etc. 
lsmod looks like this (just the relevant bits):
Module                  Size  Used by
snd_via82xx            29092  0
snd_ac97_codec         73220  1 snd_via82xx
snd_pcm               100876  1 snd_via82xx
snd_timer              24968  1 snd_pcm
snd_page_alloc         12944  2 snd_via82xx,snd_pcm
gameport                5120  1 snd_via82xx
snd_mpu401_uart         8192  1 snd_via82xx
snd_rawmidi            26532  1 snd_mpu401_uart
snd_seq_device          9164  1 snd_rawmidi
snd                    56936  7
snd_via82xx,snd_ac97_codec,snd_pcm,snd_timer,snd_mpu401_uart,
snd_rawmidi,snd_seq_device
soundcore              11232  1 snd

I've tried running modprobe, update-modules, reinstalling module-init-tools,
etc. No joy. So what do I need to do to get alsa to recognise my
architecture, if that is indeed the problem?

Thanks in advance.
Jonathan