First make sure your files are available to share. From XP help:
To share a drive or folder on the network
Open Windows Explorer, and then locate the drive or folder you want to share.
Right-click the drive or folder, and then click Sharing and Security.
If you are sharing a drive, on the Sharing tab, click If you understand the risk but still want to share the root of the drive, click here.
If you are sharing a folder, go to the next step.
Do one of the following:
If the Share this folder on the network check box is available, select the check box.
If the Share this folder on the network check box is unavailable, this computer is not on a network. If you would like to set up a home or small office network, click the Network Setup Wizard link and follow the instructions to turn on file sharing. Once file sharing is enabled, begin this procedure again.
Restart LinNeighborhood and look for your shared components. Right click on the drive/folder and choose "scan as user". You should now be able to mount whatever you need by right-clicking and choosing "mount".
Make sure you have no firewalls active on either machine. You can work with firewalls active, but obviously they must be properly set up and I'm not too sure how to do that