Windows 7 and network shares on W2K (Windows 2000)

So, I have an old Windows 2000 machine, it works, and I don't want to replace it.
The data it manages I share on the network through a normal shared folder.

No problems until Windows 7... Suddenly I can't access the share - invalid username/password is the error. It worked this morning but now it doesn't and nothing has changed...

Google informs me that the authentication used by Windows 7 now requires NTLMV2 and proceeds to tell me how to configure W7 to accept NTLM - except I have "Home Premium" on this machine and can't edit security policies (I thought I just couldn't use remote desktop connection to the machine, but we learn something new every day)...

There is, however, a registry key that can be changed or created:

[HKEY_LOCAL_MACHINE\SYSTEM\CURRENTCONTROLSET\CONTROL\LSA]

"LMCOMPATIBILITYLEVEL"=DWORD:00000001

Create (as I did) this key and give it a value of 1

Or, if it is already there, change the value to 1

The values defined for this key are:

Level 0 - Send LM response and NTLM response; never use NTLMv2
Level 1 - Use NTLMv2 session security if negotiated
Level 2 - Send NTLM response only
Level 3 - Send NTLMv2 response only
Level 4 - DC refuses LM responses
Level 5 - DC refuses LM and NTLM responses (accepts only NTLMv2)

Thanks to http://www.governmentsecurity.org/forum/index.php?showtopic=6526

for this info