Just one piece of unsolicited advice -- Go with a business co-founder who has some unique expertise in the domain/verticle you would want to pursue. If he/she had to do "market research" to determine the potential of your future product, that is usually not a good place to start. The business guy should (emphasis) know by experience, the product/market fit.
Goodluck with your quest!
I've been burned a bunch of times by working with smooth talking guys who seemed to be good at 'business' but were completely useless in practice. Because they were all talk.
There are tons of people out there with poor ideas ("its like facebook for ....")
Going out to events and looking into your existing network is a great starting point. But if you are going to be working closely with someone for 3-10 years on a project there is a lot to consider.
Mark Suster has a great post about "hiring" your co-founder worth a read: http://goo.gl/Fkejjp