can't access desktop from laptop on wireless network

I have a d-link 624 wireless router. I am running windows
xp home on my laptop and desktop computers. I can connect
to the internet with both, and I can access the laptop
from my desktop. My problem when I look at the computers
on my workgroup, I see my desktop from my laptop, but
when I try to open it, it gives me the error
that "\\desktop is not accessible. You might not have
permission to use this network resource. Contact the
administrator of this server to find out if you have
access permissions. Acess is denied" I can ping the
desktop from the laptop with both the ip address and the
computer name. I have disabled the microsoft firewall.
Any ideas? Thanks.