OK, so I am deploying a new Virtualization Infrastructure.  In doing so I ran across a problem I had not seen before so I thought I would log the scenario, in order to be of help to someone some day...

My hardware was a Dell PowerEdge2950 with an Intel Pro 1000 VT Quad NIC installed in the original config.
 

I installed Hyper-V Server 2008 and immediately went to work configuring the machine and found that the only network cards detected were the onboard broadcoms.  Now since we plan on using more than 2 interfaces, this just will not work.  I tried manually installing the drivers off of the Dell page, however I was receiving "OS not supported."  This is no doubt due to an overzealous install checker.  I tried a few different drivers and finally came to the conclusion that in order to make this work I would need to ditch the NICs or get my hands dirty.  Dirty it is.
 

Step 1:  Extract the drivers from the executable installer.  I did this using the "/e=path /s" included with the dell driver.  The same thing could most likely be done with 7-Zip or another compression/extraction utility.  7-zip is free here.
 

Step 2:  Drill down into the extracted files to find the inf file.  In my case it was under payload.
 

Step 3:  Use pnputil to install the driver.
pnputil -i -a "full_path_of_inf"
 

Step 4:  Ensure that device shows link so that you will be able to see it using the Hyper-V Configuration Tool.
 

This should work on more scenarios then I described.  Good luck.