multihoming NIC trouble

[Ext User(silicono2@yahoo.com)]

I just scored an NIC for free and tried a multihoming experiment,
unsuccessfully, connecting my P2 laptop running WinME to the
multihoming WinXP P3 desktop. It may be multihoming was never so
reliable although Windows Help recommends it for ICS. Anyway:

-I tried the cable modem from both NIC #1 and 2, either way it works.

-the cable modem also works when connected to the laptop directly

-when connecting the laptop to either of the desktop's NICs, the LEDs
on my laptop's PCMCIA NIC are all out, and WinXP on the desktop says
the network connection to the laptop is not working ("network cable
unplugged"), indicating no activity--I've used a crossover adapter as
well and it changed nothing

-my cables are all good (tested by connecting directly to the modem)

Best possibility: the notebook to PC connection needs that crossover
adapter, but it happens to be a dud? Note that the modem to PC
connection works with or without the crossover adapter--either the
crossover adapter is bad and wires the signals straight-through, or my
modem has auto uplink (I doubt the latter).

Seb