mixed OS networking

[Sleepyjohn]

I am trying to help a friend connect all their computers together.
I am confused and frustrated, so I walked away for a moment.
User has four computers and two printers, one router in their home.
1. Dell Desktop, Windows XP SP3, connecting wirelessly, has HP Photosmart7600 attached.
2. H-P laptop, Windows 7, connecting wirelessly.
3. Dell XPS Desktop, running Windows XP SP3, wired to router, has HP Photosmart 7300 attached.
4. Dell laptop, Windows 7, connected wirelessly.

All computers have internet access.
All computers can print to all printers (wirelessly for all, except for each DT connected to local PTR).
All computers can see each other.
All computers belong to "WORKGROUP" workgroup, and have different names.

UNABLE to share PICTURES from either laptop to anybody else. (XP computers or the other Windows 7 laptop)
UNABLE to share DOCUMENTS from DELL desktop (#1) to anybody else.

Comes up with message that ..... user doesn't have permissions.....
Already verified that the correct folders (Pictures, documents) were shared.
What did I overlook?

[Geek-9pm]

user doesn't have permissions.....

When you do a share you have to set permissions.
On the share pane look for the permissions.

[Sleepyjohn]

Thanks for mentioning that! 
I gave all users Read/Write/Full Control over this network, befpore I posted my original message.
Actually, there is only two users, and they have the same login for both their laptops and their desktops.
Disappointed that there are not more replies from more knowledgable system administrators.
Anybody else have any ideas?

[Geek-9pm]

Sorry to see nobody wants to get into this.
Windows networking, at is best, is good. Never excellent.
You can either:
1.) Re-do windows network wizard on every PC on the network.
2. ) Setup a network domain. (I can't help you with that)
3. Install a Third-Party tool on all most of all PCs on the network.

About the only thing that really works in Cisco Network Magic.
The free trial is 15 days, enough time to find out what is wrong.

Cisco - Home Networking Software - Set up and Manage Your Network.

It works for me. After I get the network up, I discontinue the product and the networks still works, most of the time.

[Rob Pomeroy]

In a workgroup, when connecting between Windows machines, the "client" machine will by default transmit the username and password of the currently logged on user, when connecting to the remote machine.  So it helps to make sure that you're using identical usernames and passwords on all machines.

Obviously make sure that file and printer sharing is switched on, on all machines.

Double-check the settings in the Windows Firewall (or other third party firewall).  Make sure that "File and printer sharing" is enabled in Windows Firewall (TCP/UDP ports 137 to 139 and 445 generally).