Comment 4 for bug 593472

@JeanF: I think the issue here is two-fold:

1) Your Ubuntu version is too old (Ubuntu 8.10)
2) You are using the wrong driver. You need to use the bcmwl-kernel-source driver package instead of the b43 driver. But I do not think that bcmwl-kernel-source is available in the Ubuntu 8.10 repositories

So I suggest the following:

Install Ubuntu 10.04 from a LiveCD session

Then connect the PC to the wireless router using a wired LAN connection.

Using the wired connection, install bcmwl-kernel-source in Ubuntu 10.04.