Windows 7 cant see my NAS or XP PC's

Hi

Help me please I am soooooo frustrated!

I have a new Windows 7 PC connected to a home network. I can connect to the web and 'see' various media devices, routers and Windows Vista PC's on the network. I cant see a Windows XP Laptop and I cant see my Buffalo ls-gl NAS but I can see these from other PC'S.

I can connect to specific shares on the NAS using Map Network Drive and entering \\IP address\share name and these all reconnect at logon without an issue. I just cant see the device when I click on Network from within explorer on the Windows 7 machine.

I followed the advice here

www.tutorials-tips-tricks.info/disable-and-turn-off-ipv6-in-windows/

to turn off Internet Protocol Version 6 (TCP/IPv6) on the widows 7 PC, before doing this I could not even see other Vista based PC's.

The NAS and all PC's are in the same Windows Workgroup.

I have taken the Windows 7 PC out of the Homegroup as I only have one PC so believe it to be useless anyway.

How can I get the Windows 7 PC to recognise the other PC's and in particular the NAS?

I have so far spent 5 hours trying to solve this and have searched lots of forums but I am stuck PLEASE HELP.

Thanks

Jon