I have wireless networking operational on my Dell Inspiron 1150 laptop with the Linksys WPC54GS PC card running on Linux Mint version 4.0 Main Edition. However, realize that what we call Linux is actually the operating system and applications that run on it. There are almost a infinite number of combinations and it is quite possible that even if you follow these instructions, wireless networking may not work. I’ve worked enough in Linux to realize that there are so many interactions between so many different applications that it is a wonder that anything works, much less something as complex as wireless networking. Indeed, it probably wouldn’t work in the Windows world either except for the fact that companies provide the drivers and software for you. Unfortunately, they do not do so for Linux installations. Such is life. So what this all comes down to is that your mileage may vary. Insert disclaimer here. Proceed at your own risk.
Step 1 is to read the Mint wiki on wireless networks here.
Note: wireless networking in Linux Mint 4.0 does not work “out of the box” when you are using a Linksys WPC54GS card and the Broadcom 43XX chip set. If it did, you wouldn’t be searching for a solution and you probably wouldn’t have found this post. 
Note 2: Don’t bother trying “The First Step” in the wiki because Linux Mint does not support the Linksys WPC54GS.
For me, I installed the Windows driver first. In order to do this, you have to copy the driver either from the install CD or by downloading it from Linksys. In any case, copy the three files (bcmwl5.sys, LSBCMNDS.cat and LSBCMNDS.inf) to a folder in your Mint home directory. Then Administration –> Windows Wireless Driver, and enter your password. Next, click on Install New Driver. Then browse to the folder in which you copied the three Windows files and highlight the .inf file and click the install button. Mint may go through an attempt at trying to login to a wireless network but it will fail because you aren’t done yet. At this point, if you didn’t get a popup saying there is a restricted driver available you can try two things, reboot or follow the instructions in the wiki here (the second option “With the Linux Driver” should work).
In my case, the popup notified me of the restricted driver, I opened the box that showed me the fwcutter driver, selected and installed it (you need a working Internet connection for this part because it will download a .deb file). Once installed, it asked where the firmware was. There were two choices, if you already have it you can point it to where that is stored. In my case, I chose the second option and downloaded it (the Internet address is already setup you just need to pick this choice).
At this point, the Linksys card was working and I could proceed with “The First Step” in the wiki. Although I don’t recall see the “key ring manager”, whatever that is, I was able to get logged into my wireless router and all was well.
As stated in the beginning, even if you follow these instructions, it is possible that wireless networking may not work. If so, read the wiki post and try some of the other options. If all else fails, you can post a request for help at one of the Mint forums and hope they can help you. But in any case, if I can get it to work, so can you.
Aloha!
