Looking to just build a "core server" with no display as it will just be sitting in the basement comm room.
I will remove the Gigabyte video card and use the one on the motherboard which is an nVidia C51PVG.
As a beginner, I would recommend leaving your core as a hybrid, at least for now. True most things can be done remotely, however sometimes I find it is really useful to have a physical screen, especially when it's early days. The MD part really doesn't use up that much resource if it's just sat there doing nothing.
(Also handy for doing Clonezilla disk image backups - an absolute life-saver!).
I am using an ATI card in my core (because I had one). As Thom says, nVidia really is the best bet, but where I am using it purely as a "service screen" if you like, you can get away with lots of other types of card providing you used UI1 (the first option in the AV wizard, the non-fancy one). No it doesn't look nice, sometimes the screen resolution does funny things, sometimes it appears matchbox size.... but I don't care.