[PLUG] Setting permanent eth0 IP address in Ubuntu LTS?

[Tom Sharples]

Hi, I've run into a (documented) bug using the Network Manager GUI to try to 
set a static IP eth0 address in Ubuntu : the "apply" button is always grayed 
out so it won't let me set the address no matter what I do.  Is there a 
command-line shell script or file I can edit to get this set up? Ubuntu is 
very foreign to me (I use slackware) and I'm loath to screw something up on 
a system that's going to a customer.

Thanks,

Tom S.