MoBo and graphics

[Elm]

Hi all,
I'm looking to build a quiet pc, probably starting within a week or so. I did a bunch of research six months ago, but a lot seems to have changed since then. One of the big uses for it will be audio processing, and some video editing. I was thinking of going for in Intel i5 in an Antec P183. I'm after advice on what motherboard and graphics card I should go for (I don't do much gaming, but I want something that can cope with it occasionally; video stuff and quiet is more important though).

Any ideas?

[Elm]

I'll be trying to do something similar to the Boring but Silent pc: viewtopic.php?f=17&t=62962&p=547310

Also, I forgot to mention I'll be using two monitors, possibly upgrading to three or four in the future.