Win 7 Laptop cannot access files on fileserver.

New Dell Laptop win 7 64 bit Home Premium. It is hooked up to a small network consisting of a 2003 R2 std server (used mainly as a shared file reservoir) and 4 XP COMPUTERS all part of "workgroup". The win7 laptop can see all of the computers & the FILESERVER & can also see & access a separate FTPSERVER computer ( not sure why I can't see the 2 networked printers but haven't pursued this yet). Internet works fine.
On trying to access the FILESERVER I am asked for a password to which the correct password does not work.
To verify that the network itself isn't the issue ( & I know this isn't the truest of statements) I installed two other computers (that were never part of this network) one with Vista-Home & another with XP-Home setting them as part of "workgroup" using identical computername & password as the win7 laptop. They both worked perfectly in the network. Only the laptop with windows 7 cant access FILESERVER.
Is it possible that I absolutely need win7 pro to have a chance of making this work
or any other ideas why?

This might work for you to access shares on local server. I'm not sure what you are using for your server but this might help. Do this on the Win 7 machines.

Control Panel - Administrative Tools - Local Security Policy

Local Policies - Security Options

Network security: LAN Manager authentication level
Send LM & NTLM responses

Minimum session security for NTLM SSP
Disable Require 128-bit encryption

Thanks for the reply.
However I cannot find Local Security Policy Local Policies nor Network Security anywheres in the computer. Maybe these controls are not provided in Windows 7 Home?

When I selected run and entered "local" I didn't get local security policy. I got "view local services", a folder called local storage, but nothing that related to what we need to do here.

When I type "local" in the run box of my other laptop running Windows 7 Ultimate(32bit), I do get the local security policy. Noob conclusion: without some sort of registry hack, Windows 7 pro, Ultimate or Enterprise is needed for this sort of networking...

Thoughts anyone....?

On a side note, a little program called Winlogon allows Windows 7 users to change their logon screens. It works on Windows 7 Pro, Ultimate and Enterprise, but doesn't seem to do diddly-squat(yes, i said diddly-squat...your day is complete) with Windows 7 Home Premium(64 bit).....