I'm helping a friend install linux on his IBM Thinkpad 760cd. The only thing I can get to install without mucking about with a network boot option is Debian etch. Fine.

This goes very well actually. The Xircom XE2000 10/100 pcmcia ethernet adapter is detected and activated w/o any problem and the installation completes without a single error. Because I am not about to subject even my worst enemy to GNOME or KDE on a computer with this little ram or ancient a processor I tell it only to use the Laptop and Standard System tasks and leave the "Desktop" option alone so I can install only Fluxbox, or WMaker later.

So, installer reboots the system and everything is going fine, until I try to do something needing the network. eth0 isn't started. WTF? Ok, so my Ubuntu system kept doing this, no worry, just ifup eth0. No such device.

pccardctl status -- nothing. pccardctl ident -- nothing.
cardmgr -- No sockets found (all this after I modprobe pcmcia, it wasn't loading by default for some reason).

I've looked everywhere. All I can find are instructions for what to do if the card won't intialise. What am I supposed to do when the kernel can find the pcmcia sockets and the card attached when it's the installation floppy, but not when it's the final install?

Perhaps you should also post to the debian forums:

http://forums.debian.net/