Hi all,
As many of you have found out, Vista compatibility with your CNet Pro200WL PCI Fast Ethernet is not good.  
 
After many hours of searching for a replacement driver for this NIC card, I finally found one that works on Driver Guide.com  www.driverguide.com.
 
Search for PRO200WL by CNet and you will find it out there.   Copy the files down to a temp location on the PC in question and go to your Device Manager in Windows (Control Panel), right click on the disabled Ethernet Card and select "Update Driver...".  
 
Then point to the temp location and let it search for it.   It will then find the driver and tell you it's successfully installed. 
 
Couple of things.   Because this was so arduous, I wanted to share my finding with others who I KNOW are having the same issue (Dell Take Note PLEASE!!).
 
Second, if you can bare with the ads first, and "No Thanks,..." out of them, it will eventually get you to the listing of these drivers, including PRO200WL. 
 
I hope for everyone's sake having the same issue that this helps get you back on line like me so you can enjoy Vista like you were intended to...like me. 
 
Best of luck..