Can't find XP-computer

Hi there,
Like a lot of people I have a problem with my network Xp-Vista.

I have a Desktop with Xp-home edition sp2, connected by ethernet-cabel to my
Linksys Router and I have a Laptop, running Vista, connected wireless.

On my Desktop I can find my Vista computer in my network. (Can't get into
folders yet, but that is later to be solved).

In the networkdisplay on my Vista laptop, I can't find my XP Computer.
I did ping my desktop and it worked. SO, I tried to type the ip-adres of my
Desktop in Windows-explorer and I could get into all the shared files.

So... I have a connection, but the desktop isn't displayed in my network.

Anyone idea's??