Question : networking xp and vista- xp seeing vista but vista not seeing xp

Hello,
I have two computers networked at home. one has xp. one has vista. I use at&t sbc DSL. I have a router switch. computers are networked wirelessly.
If I am on XP computer I can access shared documents on the Vista computer. But if I am on the Vista computer I cannot see the xp computer.
I have tried different things and now am totally confused.
I even am confused when I look at IP address, subnet mask, and default gateway in Vista- is not the same as XP.
Can someone tell me basic things to verify to let me at least pinpoint where the trouble might be?

thank you

Answer : networking xp and vista- xp seeing vista but vista not seeing xp

Have you downloaded and installed the LLTD (Link Layer Topology Discovery Responder) on the XP machines?  Without that, the Vista machines will not see the XP machines in the View full map link of Network & Sharing Center:

http://www.microsoft.com/downloads/details.aspx?familyid=4F01A31D-EE46-481E-BA11-37F485FA34EA&displaylang=en

Same workgroup for all pcs?  Actually sharing something, rather than just file sharing turned on?  Same users and passwords entered on all pcs?  Network discovery on?

You might be interested in looking at this question which I asked not long ago, when I was having trouble setting up my home network with XP machines and Vista in it.  It mentions all of the things needed for a wireless network with XP and Vista in it:

http://www.experts-exchange.com/OS/Microsoft_Operating_Systems/Windows/Windows_Vista/Q_22772074.html

In setting up my home network, I found I had to turn off the firewalls temporarily before trying to see the Vista machine in the XP My Network Places, then turn the firewall back on once it succeeded.  See this page:

http://www.lockergnome.com/nexus/blade/2007/04/09/vista-networking-problems-try-this/

The following page has a quite good treatment of File and Printer Sharing in Vista, complete with screenshots:

http://www.microsoft.com/technet/network/evaluate/vista_fp.mspx
File and Printer Sharing in Windows Vista

Another good article:

http://www.howtonetworking.com/vista/sharingfolders.htm
How to share files from a folder on Windows Vista