Here's the procedure i recommend to get your wifi working
modprobe -l (this command lists all supported drivers your wifi driver should be in the list)
modprobe YourWifiDriver
dmesg (this command should list your adapter for me it's listed like this :
[ 710.102000] wlan0: ethernet device 00:18:e7:06:e7:00 using NDIS driver: sis163u, version: 0x1000000, NDIS version: 0x501, vendor: 'Wireless Driver', 0457:0163.F.conf
[ 710.104000] wlan0: encryption modes supported: WEP; TKIP with WPA, WPA2, WPA2PSK; AES/CCMP with WPA, WPA2, WPA2PSK
)
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ifconfig eth0 down (if your ethernet card is eth0, disabling it temporarely will prevent conflicts preventing your Wifi to get an ip=adress, you can reactivate it later with "ifconfig eth0 up")
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Configuring your wifi whith a WEP key
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iwconfig wlan0 essid YourRoutersESSID
iwconfig wlan0 key 59d560926453e16103acdfte98 (replace with your WEP key)
ifconfig wlan0 up (activate your wifi adapter)
dhclient wlan0 (get an ip adress from the router)
dhcpcd wlan0 (alternative method in case the previous command doesn't work)
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dhcpcd -k wlan0 (usefull if you have a problem with your wifi... this releases the ip adress so you can ask a new one)
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Replace wlan0 by the name of your wifi adapter for these commands to work for your configuration...