I've been playing for two decades and have taught both guitar and music theory. I'm also an alumnus of Berklee College of Music. Knowing theory isn't a necessity, but it certainly can make things easier. I'm presently putting together a site that will incorporate some really cool teaching concepts. It's all free and there is some cool software you can download. Check it out at
http://www.texotix.com
My students have always had great results from my teaching methods so I encourage you to stop by. I'll be adding lessons on a weekly basis, if not more often than that. Cheers!