How do I access W7 drives from XP via LAN?

Running a home LAN with W7, W8 and XP computers, desiring to transfer files freely between the hard drives on all machines. Homegroup works well between W7 and W8 machines. Local network, called "LOCALAN," works well between the XP machines. The W7 and W8 machines can transfer files between themselves and the XP machines, if requested from W7-8, but any attempt at an XP machine to open a drive on a W7-8 results in access denied.

On W7, using the Network and Sharing Center, options are set as Network = Work Network, Connections = Local Area Connection. Network discovery = on, File and printer sharing = on, Public folder sharing = on, Media streaming = on, File sharing connections = 40- or 56-bit encryption enabled, Password protected sharing = off and Homegroup connections = Use user accounts and passwords. I haven't been concerned with W8, figuring when W7 works, so will it. The physical LAN is fully private and protected, so the machines have been configured neither with multiple accounts nor any password. Upgrading from XP on the remaining machines is impracticable; they don't have enough RAM.

On W7 the D: and E: drives (large hard disks) have their properties set to Shared by Everyone with Full Control.

What have I overlooked?

Thanks for your attention.

Additional information:

All machines on this LAN have static IPs.

The XP machines can access some files in W7's "c:\users\public" folder. Ironically that folder is not even marked as shared.

It occurs to me that on W7-8 I could in principle copy between the D: and E: drives and c:\users\public for the XP machines to access, and vice-versa. But these typically are gigabyte files. I cannot believe that computers should be so inconvenient to use!

2xg,

I have carefully read the recommended Microsoft guide and believe I've followed its instructions to the letter, including installing the "LLTD" hotfix on the XP machines. That caused them to appear on the W7 Network Map but did not fix the access denied problem.

The workgroup has long been set up. The W7 Control Panel>System and Security>System shows Workgroup: LOCALAN.

Thank you for trying to help.

Problem solved!

Searching the Web, I ran across an article in www.sevenforums.com, of all places, with the answer. The thread is succinctly titled, "XP accessing Win7: Access is denied."

On Windows-7 and -8, it turns out that you must alter the disk drive properties in the _Security_ section -- nevermind the sharing section! -- to add "Everyone" to the "Group or User Names" list, then allow it Full Control. Note that "Everyone" is not the choice of a radio button; you must type it into the list literally without being prompted to do so.

Really, Microsoft! I'd love to hear an explanation of who benefits from requiring such a complex and unintuitive procedure to permit communication with legacy software. By now the world must be full of LANs that combine Windows-7/8 and -XP machines.