I'd suggest to install using this netboot ISO:
if he has an already running installation the easiest way would be to change in /etc/apt/sources.list all occurences of "sarge" or "stable" to "etch" or "testing", run apt-get update and afterwards apt-get dist-upgrade.
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"Schon vor dem Come-Back von Modern Talking wusste ich:
Dieter Bohlen ist der Preis der Freiheit."
Heinz Rudolf Kunze