"account currently disabled" when accessing share, even before logging in

Take a look at the Credential Manager on the XP machine.

Control Panel -> User Accounts -> Manage My Network Passwords (on left of screen)

Here you will see a list of stored usernames\passwords and the server\share that they are used against.

Delete the server\share in question, and next time you connect to the share it should prompt you for a username and password.

Edit:

Another thing to check would be the number of open sessions on the Windows 7 machine hosting the share. Windows 7 has a limit of 10 concurrent sessions.

You can check this in computer management on the Windows 7 machine -

On the start menu right click "computer" and choose manage, then navigate to System Tools - Shared folders - Open Sessions.

It sounds like your client machine is not giving you the opportunity to specify credentials for the "share" username that you have created on your server.

In a workgroup environment, the easiest way to force Windows to log into a network share with specific credentials is as follows:

net use \\server\share /delete
net use \\server\share /user:server\username <password>

Mapping a drive letter to the share is optional, e.g.:

net use \\server\share /delete
net use S: /delete
net use S: \\server\share /user:server\username <password>

In your specific case, the username above would be "share".

By the way: how many clients are accessing this "server" concurrently? Windows 7 has a limit of 20 connections, up from 10 in Windows XP. It's been a long time since I've worked in an environment that was using a Windows client OS as a file server, but it seems plausible that, if the limit were reached, additional connections could be denied with a non-intuitive error message.

This is caused by there not being a password on your account on the pc you are trying to connect From

Click through Control Panel - user accounts and set a password for your current login

then when you try to access the network share it will prompt for a username and password. use the correct one to access the share at this point.