Can't see XP machine from 2K on netwrk

I have a home network with a DSL modem and a 4 port Linksys router. The DSL
modem has been configured to let the Linksys do the router stuff. I can see
my Win98 desktop on the network from my 2000Pro desktop and vice-versa. I
had to run NetBUI for that, YUK!

Also, I had another 2000 machine that I could see on the network from the
2000 Pro desktop. I just replaced it with an XP (not XP Pro) machine.
Everyone is configured for a Workgroup named WORKGROUP.

I cannot see the XP machine from my 2000Pro desktop.

My friend brought over a Win2k laptop(don't remember if its pro or not) he
could not see any machines in network neighborhood. However, the XP machine
could see the laptop. We were trying to copy files onto the laptop from the
XP desktop while at the laptop keyboard. Because the XP desktop could see
the 2000 laptop, but not vice-versa, we had to sit at the XP Pro machine and
copy files to the laptop.

My Win2000Pro desktop could only see itself and the Win98 desktop. The 2000
laptop could not see the 2000 Pro desktop, however, it could ping it.

They are all configured with tc/pip and dhcp. Any ideas?

Jim