Bah! I'm totally new to this and I'm loving it, with a few quirks. Setup as follows
Dell Inspiron 640m or E1405
Core 2 Duo T5600
Intel 945 chipset
Dell 1390 WLAN mini-card

I've researched on the net and here, and everyone seems to have this particular wireless card working flawlessly. Under system info>airport card information, the card is recognized as "airport extreme), USA locale, firmware version is "broadcomm bcm43xx 1.0" (why is it broadcomm) and under current wireless network it says "airport is currently turned off".

Airport is not present under "Internet Connect", apple says this is probably due to improper installation of wlan card. this isn't accurate as the card works fine under winxp. I've also updated the airport software through software update, but to no avail.

As for help, all kinds is welcome. Since I'm totally new to this, there may be some totally general fix I may have had to done, equivalent to installing a driver or something, that I haven't done. Basically, don't be afraid to post something ludicrously obvious that I should have done, heh.

take a look:

http://forum.insanelymac.com/index.php?showtopic=44114

It helps me a lot... could be the same problem...

Thanks, that worked! Although I can't seem to connect to my wireless network at home. It detects it, but I enter my password and it says it can't connect. Any idea what's going on?

munim, i've got almost the same setup as you....every time i install MacOS on my 6400, for registration, it does detect my home network, but i can't connect, so i just skip network setup....i've tried the above method, but to no avail yet....have u had any luck?

Which kind of protection you have on your wireless network (WEP, WPA, etc)?

jackmup: no luck yet!

t.skid: wep, 64 bit I think. I think that may have something to do with it because I'm (temporarily!) using some unprotected neighborhood network that's working fine.

jackmup I have a Truemoblie 1450 in my Dell 9300. I always disable it in the Bios before I install, replace the IOnetworking Family Kext and the IOPCIFamly kext. repair the disk reboot and then shut and enable the wireless card and then it finds it fine. I've never tried to repair it if I forgot to disable before I started.

GimmeRed.....? i'm sorry, but i don't quite follow you...i've modified one of the kexts, using the method Here, but that only messed more up. can u explain what you did? i'm a lil new at this....thanks

well I solved my problem. It turns out that I was using 64bit encryption, and airport can only do 40 and 128 so I switched to 128 and it works!

jack I'm more of a drag and drop sort.

You can get a lot of the files you need here.

http://forum.insanelymac.com/index.php?showtopic=36886

Open the zips and drag them to your desktop.
Open your disk with you osx install, open the system folder,open the library folder.open the extensions folder and find the kext file that you want to replace and drag it to the trash. In this case it would be the IONetworkingFamily .kext . It will ask for your password. Then drag the replacement kext file back to the folder. Click on authenticate type your password again. Repeat for the IOPCIFamily kext.
Next go to utilities disk utility select your osx disk and repair disk permissions. Reboot your system.

If you do need to modify a kext you can drag it to your desktop. This will create a copy. Go into terminal and modify this copy. If nothing else this is a good safe way to practice using sudo commands.