Debian Etch currently (and presumably never will) install on an ASUS P5QL Pro motherboard, and presumably related boards. I have succeeded in getting an AMD64 install in the following way (warning; kludge to follow):
Read it here
Of course, most of this wasn't required in hindsight. Key points, though:
You need 2.6.27 (maybe 26) for the atl1e driver for your network card. My suggestion is to use a chroot system like I did, but do it properly first time. Note that the driver supplied on-CD compiled fine under Ubuntu, so if you can get your system installed by other means, you may be OK.