Do both windows computers have airport utility loaded.. if not please do so.. as the utility will include bonjour for windows which helps you get to local disks.
Is the laptop setup to home, work or public location.. it must be home.
Is the firewall turned on.. turn it off.
Open windows explorer in the computer that doesn't work and type the name directly into the address bar.
\\AEname or \\AEipaddress Where you replace with actual AEname.. SMB compatible please.. no spaces short and pure alphanumeric.. or the IP address.
No go, open a command window and type.
Ping AEipaddress eg by default
If you get no response you have connection issue.