Hi WSMassive welcome to the site
I have the
Linksys Wireless-G(WMP54G ver4.1) PCI Adapter. My Install CD has Version 4.5 labeled on it.
In the begining I was installing the software in XP. First install the software without the card plugged in. Then turn the computer off and install the card. After a few months I started using windows wireless utility because Linksys software was using more and more memory the longer the computer was running. When windows detects the card point to the driver folder on the install CD. I didnt install the CD just pointed windows to the XP drivers.
When I started using Windows 7, I never installed from the CD. I pointed windows to the Vista(32bit) drivers I downloaded from Linksys for the "WMP54G Ver4.1". I havent had any trouble using the card. I know you said you have ver4.0 and I didnt see Vista drivers for this version. You may need to run in
XP compatibility mode.
If you do not have an Install CD, I could create a ISO image of my CD and send it to you somehow. My CD has the ver4.0 and ver4.1 drivers