might be that you haven't enabled any shared resources on the two computers. You need to right-click on a folder and select 'sharing and security' to do this.
Presumably you have given both computers the same workgroup name - MSHOME - and different computer names?
Software firewalls can sometimes interfere with network connections - try disabling them on both machines and see what happens. If your network is OK you can then configure the firewall settings to allow the connection.