Windows 7: Cannot get new Win 7 to see existing networked XP PCs

I'm trying to read alot of posts here and while many of the problems are familiar, I'm not seeing my answer so far.
I have a new Win 7 PC. I have an existing two XP PC home network. The existing network successfully shares files and a printer. Integrating the new Win 7 PC into my network, I have been half successful. I have internet access through the existing router on all three PCs and I have printer access on all three PCs since moving the printer to the Win 7 machine. Both XPs can see the Win 7 machine on the network.
This is where things go off the rails for me though. The Win 7 machine cannot see anything in its network except itself and the router. Keep in mind that certain apps can see back and forth. Windows Easy Transfer was able to see my XP machine from the Win 7 machine and move all my files over just fine. Norton NIS 2009 can see all 3 PCs from all 3 PCs and interact with each perfectly fine.
Likewise, the XP PCs aren't quite there yet either. They alternate between having 100% access to the Win 7 public USERS share and having no access at all - with no changes being made to the setting. Currently it is not accessible and I might not have permission to use this network resource. Interestingly with the XP to Win 7 connection fails, it fails on both XP computers at the same time. Either both work just fine or neither works at all.
All three PCs are in the same workgroup. All three have the same user account names and passwords. In Win 7, Network discovery is on along with all the other Advance Network Sharing features. I am currently sharing the Win 7 shares with Everyone. I have tried shutting the firewall off and leaving it on. All three are set at Full Trust for NIS 2009.
Help, I'm pooped.

From experience, sometimes the "Computer Browser" function just does not work

Have you tried on the Windows 7 machine creating a shortcut on the dekstop using the text \\Name-of-XP-machine

Also have you tried opening a command box on the Windows 7 machine and typing ping Name-of-XP-machine

Jonathan

Quote: All three have the same user account names and passwords.

And there lies the problem. You absolutely need to use a different machine name on all machines. They won't show up consistantly otherwise. So you just need to change the machine names on the XP machines so they do not match each other and don't match the name used on the Windows 7 machine.

They should all be sharing the same "workgroup" name but not the same machine name.

First, I rebooted everything at some point and so far my WinXP PCs have full access to the Windows 7 PC. All that remains is that the Windows 7 PC refuses to see either WinXP PC on the network.

I attempted to create a shortcut to a WinXP. New > Shortcut > "\\XP-machine" > Next, only to be told "\\XP-machine cannot be found." Perhaps I'm not creating the shortcut correctly.

This is what I get when I Ping from Windows 7 to WinXP, I also get a sucessful Ping from the WinXP to the Windows 7.

C:\Users\Trine Curtis>ping XP-machine
Pinging XP-machine [192.168.1.2] with 32 bytes of data:
Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
Reply from 192.168.1.2: bytes=32 time<1ms TTL=128
Ping statistics for 192.168.1.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

I also found this Microsoft article Networking home computers running different versions of Windows which has just about everything I've seen mentioned before and tried except for a long list of ports in my firewall I might need to open to be successful. Overkill?

Thanks!

Yes, you need to use workgroup or public file sharing when sharing between different Op systems.
But, this fact has nothing to do with your problem.

Please change the names on the XP machines. Please follow advice "already given" if you want the problem solved.

Hmm. Ok, I can change all the user account names on my old XP desktop to Name-XP easy enough. However, I'm a little fuzzy why the affects my Windows 7 from registering the existence of the WinXPs altogether. I definitely see how this might affect folder sharing (and confusion in general). All of my shared folders on the XP systems had unique names and do not also appear in my Windows 7 system.

I'll give it a whirl.

If all the user names are the same then Windows cannot identify them on the network. I've already tested this out on XP and Vista machines. There is no way networking will worked correctly unless each machine has a different user name. But it helps if they are all using the same name for the "workgroup".

Using the same user name made the XP or Vista machine not show up every single time for me.

Take a breath. I was posting that previous response when you responded. The "already given" advice hadn't even been read yet.

Ok. I have now changed the duplicate user names to three different ones. Name (on Windows 7), Name-XP (on desktop XP), and Name-lap (on laptop XP). The three different PCs already had unique names.

Under Network on Windows 7 I still only show the Windows 7 PC and the router. What am I not getting about this?

Sorry about the confusion but I assumed you were responding to me with something that made no sense.

You also need to enable network discovery and file sharing on the XP machines. Make sure all of the steps are checked in the pictures below. You can use either workgroup or public file sharing but not homegroup because that only works with Windows 7 machines.

The Windows 7 is completely enabled under the "Change advanced sharing settings" and is set up as a Workgroup with the same name as the two XP machines.