Every bike of or frame I've ever bought came with a headset. So I've never had to worry about it. I just used what it came with.

Now I'm building up a bike for my gf and it didn't come with a headset! Are all headsets created equal? What makes a good headset 'good'? And what headset do I even have to get for a Van Dessel Rivet? I see all this stuff about threads/no-threads, integrated/non-integrated, different diameters...and on top of that, this bike's head tube tapers so it's wider towards the bottom.

Any help/advice?

Thanks!!!