I finished upgrading my Dlink DNS-323 to Debian Lenny today. I followed the instruction at:
The install took quite a while, I selected the standard package list. Then because it gets quit hot here in Griffith I really wanted to have fan control back, so instruction here were also followed.
As I wanted to install to an 8GB Flash drive I had handy I first uploaded the netboot.img firmware, turned off the DNS-323, removed the hard drives and left only the flash drive inserted, then powered up and followed the installation instructions.
I like keeping root on the flash drive as the hard drives can be stopped all day when not in use to save temp and power.
Fans are also controlled by lm-sensors and the unit seems to run about 47degC most of the day.
I use the unit mostly for irc (screen/weechat), rsync backup target and samba media server. It handles all that pretty well but I do notice it bog a fair bit with only 64mb ram and hard drive transfer rates are not as good as I am used to, but on the whole a great little unit (now that it runs debian).