KANOTIX64 is the way forward,
I tried the 2005-01 release, and it worked a treat straight out the box.
The problems i ran into were with non-debian software and a shortage of debian 64 .debs, such as the Flash plugin for Firefox - there isn't a 64bit version yet.
Soon everyone else will catch up and we'll be dancing the 64bit dance along with our 32bit brothers
but I am, for now, using the 32bit KANOTIX as it is a fine Debian distro!
1 Gb RAM
ASUS K8N-E Deluxe
and a few other bits....