PCI ethernet cards

[k]

Hello

Have any of you used PCI ethernet cards in your Macs? Is it like 
everything else, in that there is no generic driver for the Mac so 
you have to pay five times as much for one or two brands of card that 
ship with drivers?

In a nutshell, is it or is it not possible to use a generic ethernet 
card in a Mac? I've had a difficult time trying to get a clear answer 
to this question.

Cheers, k.
--