Are you operating a firewall on one or both computers? If using the Windows Firewall, you have to add an exception (start > control panel > security OR windows firewal) and go to the exceptions tab and make sure "File And Printer Sharing" is checked.
Make sure your NetBIOS settings are up and running. Go to your Local Area Connection, and right click it for properties. On the first screen make sure your Client for Microsoft Network, TCP/IP, and Windows File and Printer Sharing are all checked. Go to the TCP/IP and click the properties button. On the bottom of that page, click on the advanced button. Go to the WINS tab and make sure NetBIOS is set to default (on). Most of the time, I would also recommend that the computer DHCP settings are set to Dynamic to let the router assign them, unless you have purpose for static IP usage.
Try all those steps, restart the computers, and pull up Command Prompt on both computers (Start > RUN : cmd.exe) On one computer, type in "ipconfig" and find it's IP address. On the other, type in "ping 192.168.1._" (fill in the blank with the IP from the other). If this works, the computers are seeing eachother. Repeat the previous post with opening up windows explorer and typing in \\COMPNAME and see if that works.
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