I've got a friend who is a giant nerd, loves the concept of building miniature armies, set pieces, and the like. She has no idea where to start.

I've warned her away from Games Workshop.

She's a fan of Dwarves. So...

Where should she be looking? Who has Dwarves, a good ruleset, unpainted Minis, and isn't GW?

Try mantic. I've heard good things about kings of war. Their dwarves look good IMO. Mantic's figs aren't quite as good as GWs for modelers though, they have fewer pieces so less poseability but the dwarves at least are well sculpted and a lot cheaper.