Windows 8 does not support old WEP encryption... Change your router to WPA2-PSK, and forgot the old network before connecting... Windows 8 doesn't have a 'Manage Wireless Networks' like 7 did, it may be difficult to forget, with the built-in WiFi manager you can only forget a network you're connected to, or possibly all networks like in 7... Click the WiFi icon by the clock, right click your network, and look for 'Forget this network'... If it's not possible to forget it, try changing to a unique SSID, and connecting to that, making Windows 8 have fresh settings for the newly created network...
G75VW-DS73-3D | 670m 3GB | 32GB RAM | 1TB RAID-0 2 x 830 512GB SSD DualBoot | Killer-N 1103 WiFi