Win 7 clients Can't see/connect/share with Windows XPP systems

can someone point me in the right direction here? have a network[s] that is almost all wireless with 2 windows 7 clients [ultimate x64 and home premium x64] and two, sometimes 3 windows xp systems, a vista system, phones, etc.

Something changed recently and resulted in the win7 Ultimate system losing visibility to the main win xpp system.
- previously, I could share files between those two, mainly through the 'shared' and 'public' folders. Now I cannot pickup the XPP systems at all from either Win7 System.
- The only significant change I can think of is that I added a win7 Home Premium system to the mix, 'joining' the Homegroup that had already been established on the Ulitmate rig. I did not setup any new Homegroup via the Home Premium notebook.
- Another thing that puzzles me: the Ultimate system identifies its network connection by the name of the Windows XPP established network - Mshome2. The notebook identifies the same network by the Wireless AP name. I'm wondering if that amounts to the "same" network as Windows 7 identifies such, or to those systems are these indeed two 'different' networks, howbeit operated by the same routers?
- The two Win7 systems can see/access one another. I turned 'On' Media streaming and Media sharing on both of the Win7 systems.
- From the XPP systems I can pickup the Win7 Ultimate rig but I have not setup a separate Login for it.
- From the XPP systems I do not see the Win7 Home Premium system at all. The XPP systems are networked by the same Wireless AP as the Win7 system.

I'm a tad confused at this point. Someone learn me pls.

I believe you should only link XP and W7 on a workgroup basis. If there are multiple W7 machines involved, and you have altered a Homegroup setting, I would have to say that it might be easiest if one of them was equipped with dual LAN ports and acted as a share point for the Homegroup; and that that same W7 machine was also on the XP Workgroup.

However without a network schematic it'd be hard to tell what you're working with for sure.

How? that is, how to "link ... on a workgroup basis"? and what caused the change? what was working is no longer working.
I don't know the reliability of the site, but the "how-to-geek" has an article on this subject, with 800 or so mostly positive responses - and what he outlines there concerning this topic is how I have it setup, but the clients are blind to one another, as I described. There is one very critical sentence in the article Share Files and Printers between Windows 7 and XP - How-To Geek
"If you want to keep it enabled make sure there is a log in account for the other XP machines and they have a password." He is speaking of the option under Win7 advanced settings re: turn on/off password-protected sharing of public folders. What I don't get is this: Is he speaking of setting up another User Account on each of the Win7 clients for the XP users to log-into? If so, why not use the Guest Account for that purpose. I thought I would try it, but here is what happened... one of the XP machines can "see" one of the Win7 machines, so I hit it and was challenged one time for login credentials: when I gave it the credentials if failed, and thereafter seemed to be 'marked' so that I no longer get the login/password popup, i just get an error.

Solved, but I don't know what exactly 'solved' the problem.
For future searchers - I feel your pain. This kind of issue is posted a hundred times a day in various forums.
Microsoft just didn't do their homework IMO.
Why, for cryin' out loud, would they hide the Workgroup settings, and not even show a live Workgroup under the Networking & Sharing control panel app? ... I would love to hear the rationale.

For whatever reason, I was able to get a Logon from one of the Windows XP machines to the notebook loaded with Win7 Home Prem x64. I logged in. Once that succeeded, then both Windows 7 machines suddenly were able to detect/identify all the windows xp systems. From the W7 Home Prem system I was then able to access shared files on each of the windows xp systems [why?].
However, the Win7 Ultimate x64 desktop was still returning errors if any Win XP system attempted to logon. The Guest account on that Win7 system was enabled. [for the first time ever - I just enabled that one yesterday while trying to solve this]. With the Guest account enabled, the error message changed to "User has not been given permission to access this resource". So today I turned it off. Then, thinking the issue might be IP stack or driver related, I installed a USB wireless adapter in addition to the hardwire that the desktop W7 system was using. I still was unable to access the system. So I disabled the wired adapter and rebooted. Still unable to access, but the error changed to "network path not found".

I rebooted again, re-enabled the onboard hdwe NIC, and fetched a few Win7 updates I wanted. After that started I went back to work on the network issues. From one of the Win XP clients [this one happened to be Home Edition] I accessed the belligerent Desktop and suddenly got a good Logon popup. Logged on with the main account credentials, and it worked.

I have no idea what the underlying issue is, but it worked. It must have something to do with Windows 7 networking policies that differ for wired vs wireless access.

That's why I mentioned without a network schematic diagram it's pretty hard to work out.

Permissions on different machines are also in play, as you've found.

IMHO Microsoft could have released software to make networking XP/2000 to W7 a lot easier.

I suspect the thinking is "let's force users to upgrade..."

Some users in your position have also lost network capability when W7 updates are rolled out.

I wouldn't care to be an admin' on such a hybrid network, I'll be honest!

no kiddin'.

I have another thread here that NObody has responded to, re: an application which is designed to run in a server mode [whatever that means] on a Windows XP system [not Server, just regular ole Win XPP]. If then somebody in the practice upgrades a client to Windows 7 - will it work? Or, how would one go about setting it up to work? I guess you could, as fallback postion, sorta get there by installing a RAS package on the Win7 machine - seems messy.

Something which might interest you could be using Mikrotik Routerboard O/S in lieu of ordinary ethernet switches, in theory you could tone down the security on W7 workstations and allow the Routerboards to handle that - leaving you free to hook up pretty much any piece of hardware you wanted to...

Anyway, glad it's working (for now!!!)