I've got a lot more experience with Linux than with Windows NT/2000. I've been doing Linux servers since at least 1997 and it's been like this every time I move from one distribution to another or one kernel rev to another or the hardware changes substantially. This effort was not at all unexpected.
The next one? Of course not - what do you think I wrote that 32-page (11 point) manual for? My health? The next Sarge install won't be much more difficult than the mentioned W2K one - until Sarge is seriously revised (I've already started the 2.6 kernel version manual) or becomes obsolete.
The Sarge manual was completely rewritten from the Debian Woody one which was mostly rewritten from the Caldera 2.4 one which was mostly rewritten from the Caldera 2.3 one which was revised from the Caldera 2.2 one which was rewritten from the Caldera 1.3 one.
Oh, yes, and I've got a Red Hat Enterprise ES manual to write in a month or so when I move a client from RH7 to ES.