ASUS P4PE Broadcom 440x 10/100 Controller Link Down

I have a P4PE motherboard with a Broadcom integrated controller. I've
had it linked via ethernet crossover cable to a Win98 machine for a
year or more.

I have recently reinstalled WinXP on the P4PE. Now the ethernet link
doesn't work. I've been looking around online and I can't find, or
remember, how to make the link work again.

When I run the Broadcom network test, I get a "link down" error. Do I
just need to install some protocol? Nothing has changed in the
cabling etc.

Sorry if this is a really dumb question. I fear it may be, if only
because I think I had to struggle with this last time around, too, and
evidently I did not keep notes. This should take care of that.