Cannot share xp files or printer on vista laptop

OK here goes, sorry if this has been answered before, but I can't seem to be
able to successfully add my daughter's new dell latitude notebook running
vista enterprise service pack 1 to our existing wireless home network which
consists of 2 dells running xp home and 1 dell running xp media center. I am
using a linksys router with the media center computer, and all 4 computers
can connect to the internet. The xp machines have been sharing files and
printers and still can. I would like to share files and printers on the xp
machines with the vista laptop. I have read the information from microsoft
at and have my
network set to private on the vista computer as well as turning on network
discovery, file sharing, public folder sharing, and printer sharing. I
changed the vista workgroup to mshome to correspond with the existing xp
network. Two of the xp computers are using norton security center and I have
added the ip addresses of all 4 computers to the trusted network list. The
xp media center computer has McAfee Security Center and I have allowed the ip
addresses there as well. I can see all computers including the vista laptop
on the network from the xp machines and can still share files among the xp
computer, but cannot access the vista (I really don't even need to). When I
try to view computers and devices on the vista, I only see an icon for the
router, and the vista itself. When I select view full map, I can also see
one of the xps (one of the two using norton). All four computers can ping
each other. Any ideas about what I'm missing?