Just reformatted computer and now unable to view other computers

Hey,
so my brother gave me a new motherboard last weekend and I had to reformat consequently, since then however I have been unable to view or access my netbook or network drive. Before reformatting I was running on Windows 7 ultimate x32 and I am now running on the same however in x64 instead. I know that my network is working as I can access my network drive through my netbook but I am unable to see my computer or netbook through both devices, but seen as my netbook was able to see my pc prior to reformatting I am pretty sure it is an issue with my computer.

I have done all the usual checks through the network and sharing center to ensure that everything is shared correctly and that network discovery is turned on.

I have reformatted before and sometimes suffered with the same problem but after tinkering around I have been able to fix it so I am guessing it is something to do with the change over to x64? Any help would be appreciated as it will be annoying not being able to access my files especially those within my network drive without having to use my netbook instead just to be able to use it!

Cheers

Ellie