A few things to try. If you open up a root konsole (i.e. open konsole, type "su", enter root password).
1) First, make sure the module is loaded for the wireless device. In the root konsole type "lsmod | grep 4965" (all without quotes).
The modules loaded should be iwl4965 and mac80211.
If it comes back blank then try loading the module manually by typing "modprobe iwl4965" into your root konsole.
2) Make sure that the network interface is up. In root konsole type "iwconfig". Hopefully the wlan0 interface should be listed. If it is not then check that your wireless is switched on. On my laptop, I have a button that I sometimes press to turn the wireless device on and off.
If the wlan0 interface exists then try typing "ifconfig" into the root konsole. If the wlan0 interface exists in that list then you are in business. If it doesn't exist then try typing "ifconfig wlan0 up". Next try typing "ifconfig" again and see if it exists. You should get something like this if the wireless interface is up:
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:44393 errors:0 dropped:0 overruns:0 frame:0
TX packets:44393 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:67722939 (64.5 Mb) TX bytes:67722939 (64.5 Mb)
wlan0 Link encap:Ethernet HWaddr 00:90:4B:9F:02:F6
inet addr:192.168.1.10 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::290:4bff:fe9f:2f6/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:66781 errors:0 dropped:0 overruns:0 frame:0
TX packets:36438 errors:0 dropped:0 overruns:0 carrier:0
RX bytes:70467243 (67.2 Mb) TX bytes:3315440 (3.1 Mb)
Hopefully, by now your wlan0 interface is up and if you type "iwconfig" into your root konsole you should get something like this:
lo no wireless extensions.
wlan0 IEEE 802.11g ESSID:"my_essid" Nickname:"blacktop"
Mode:Auto Frequency:2.412GHz Access Point: 00:12:17:39:7F:F3
Bit Rate=54Mb/s Tx-Power:25 dBm
RTS thr=2347 B Fragment thr=2346 B
Encryption key:0123-4567-89 Security mode:restricted
Link Quality:100/100 Signal level:-37 dBm Noise level:-256 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:1043 Invalid misc:54297 Missed beacon:0
3) Scan for wireless networks. If your wireless interface is up, as in step 2, then you can scan for wireless networks by typing "iwlist wlan0 scan" into your root konsole. You should get something like this:
# iwlist wlan0 scan
wlan0 Scan completed :
Cell 01 - Address: 00:05:5D:F1:E6:DC
Frequency:2.422GHz (Channel 3)
Quality:0/100 Signal level:-30 dBm Noise level:-256 dBm
4) If step 3 was successful and you have found wireless networks then you should beable to connect to the Internet. First, in the root konsole type "/etc/init.d/NetworkManager start" (This ensures the network manager is running in the background). Next, in the root konsole, type "rc-update add NetworkManager default" (This ensures the network manager runs on every boot)
5) Now you want to start knetworkmanager. It might already be running and present in the system tray (in the top right of the screen). If it's not running then launch it from the kmenu->Internet->knetworkmanager. It should appear in the system tray (top right of screen). You then click on it's icon, in the system tray, and choose which network to connect to.
I hope some of this helps in your quest.
All the best