Well, if you want to run Avid buy a certified system, don’t build your own. Especially if you don’t know much about computers. If you insist on building your own, decide what version of Avid you’re going to buy and go to http://www.avid.com and do a search for the system requirements for that particular software. Then build your computer based 100% only on that–don’t go for a “faster” or “better” card that “must work because it’s so much better than the one Avid recommends”. It probably won’t.
Off the top of my head, nVidia FX1400–it’s approved for Xpress Pro and Media Composer. If you’re going with Avid Liquid, I don’t know. Not familiar with it. But we have the FX1400 at work and it’s approved and works.
Break out boxes–only Mojo or Mojo SDI. If you go with Media Composer you can get the Adrenaline box but be prepared to pay a lot of money. Nothing else is approved to work with Avid and, as far as I know, nothing else works. At all. It’s all Avid hardware and software or nothing.
As far as getting a video card that outputs to two monitors and a client monitor–there isn’t one. At least, not that I know of and if there is one it’s not on Avid’s approved list.
Start checking Ebay or HP refurbished for an HP xw8200–it’s a great system, certified (make sure it matches Avid specs exactly), and it’s getting cheaper by the day because they’re out with the 8400 now. If you plan on editing for money and not for fun–BUY CERTIFIED. If you plan on editing for a hobby and not for a job, you can build your own. But your hobby might not be much fun because you’ll probably spend a lot of time troubleshooting.
Just some friendly advice. Avid is incredibly picky about what it wants, but give it what it wants and it can be a workhorse.
Mike.