Re: debian on an NAS server
Check out http://danmacs.blogspot.com/2006_03_01_archive.html
This pretty much covers the basics for installing debian.
A couple of points. You do need to alter the serial configuration and copy it to pxeconfig to enable the console on ttyS0. You don't need to worry about the crossover cable if you have a switch or Broadband router with spare ports. Just connect the server straight to the network on eth0. Also I have found that if you install in "expert" mode (you may have to enter this blind), and then select installer components and select network-console. You can then continue the install via SSH (follow the prompts to configure it). Don't try to run stage 2 install inside stage 1, my server kept on hanging.
I hope this helps.