I am in the process of setting up three debian woody mailservers on Dell 2650 machines. After searching on google I came across an net-install CD for Debian woody which was designed for Dell servers and it installed without a problem. Unfortunately I did not make a note of where I found it. But I have a copy available atftp://ftp.sun.ac.za/iso-images/debian/dell/debian-dell-2.4.25.iso
Information about linux on Dell hardware: http://linux.dell.com/ Download site for install CD: http://oregonstate.edu/~kveton/debian/ -- Martin Eian