As always, thanks for assisting...
I just recently (and very expensively) purchased a HWIC-1ADSL for my 1841 router.
Unfortunately, it doesn't display in the configuration - nor any lights appear on it for power/link.
My first guess is I need to upgrade my IOS. The current version on my 1841 is 12.4(17). Which appears to be pretty current.
Could somebody please point me in the right direction?