Any video card will be fine provided they have support for windows 7/vista. Those drivers should work with windows 2008 server.
For windows 2003 server I've had windows xp drivers work just fine, but generally speaking any video card should work.
If you need autodesk support for example and they require quadro video cards then you'll have to get quadro video cards for "official support". The reason why is because of how the drivers are written is more fine tuned for development rather than gaming.
Could anyone recommend two other video cards that officially support windows server OS such as Server 2003 or 2008 besides the NVidia Quadro series?
Any nvidia geforce 200 series video card will have official drivers for win server 2003 64 bit.. As for win server 2008, am not sure if the geforce line will ever get official drivers.. Though i think the drivers for vista 64 bit will do just fine..
As a suggestion, you could go to a website, like NewEgg, to look at server motherboards. You could then see the embedded GPU chipsets those mobos have. All of these will be supported, in all likelihood by the server OSes you are inquiring about.
Also, both OSes will use just about any GPU with standard VGA drivers. The GPU prowess of most servers really isn't an issue since they are usually only used when maintaining the system. I typically configure my servers via remote desktop.