Welcome to the Forum.
I've set up my 3945ABG using a howto on these forums by Strikeforce. That involves me in doing part of the howto each time the kernel changes, but its been very successful for me.
I'll post the link to that if necessary, but Strikeforce has created a new howto as precompiled modules for this card have become available at the freshrpms repository.
The new howto is here:
Note there are two steps to go through. Enabling the repository and then setting up the network.
Post back if you have any problems - or to report success.