LTSP woes with Lucid Lynx

[Andrew]

I have burned a CD image of my alternate install ISO for 10.04 and used
that to boot up one of the clients in rescue mode, and (re)discovered
that there are TWO network interfaces on the machine, eth0 and eth1,
only one of which [eth0] is active. That is of course the PXE card which
is used to grab the image.

What would happen if on boot the WRONG interface was selected? Would
that cause the blank screen?

Is there any way in which to force the boot up sequence on the client to
always select eth0?