Processor

So, how does one go about choosing a processor? I've decided to build a computer to familiarize myself with hardware, and this is really the one thing I know nothing about. My mobo is AM2, and I'm thinking of getting a dual core. But beyond that, I'm lost. HALP?

OP here. The mobo isn't what I'd have picked for a first or even second choice, but I'm on a bit of a budget and a friend recomended it to me (http://www.newegg.com/Product/Product.aspx?Item=N82E16813138026)

One thing to note is that I'll won't really be using this for gaming. I'll be watching and editing video, photoshopping, and listening to music, mostly. I'm hoping to spend less than $100 on the CPU, but I can go up to $130 if that's the only way to avoid AIDS.