ponyboy96 - 5:10 pm on Sep 30, 2010 (gmt 0)
To answer the OP's question, I think you need to be doing all of the above. It's all a part of your marketing mix. For social media to work, you need to have a product, service or brand that lends itself to that channel. Not all businesses can or even should be there. SEO or PPC works for just about any business with differing results, but it does work and is relevant.
Here are my personal thoughts, social media is a passing fad. This year the flavor is Facebook and twitter, next year it will probably be something else. As someone else posted, do you remember MySpace and Bebo?
As a company, you should be spending most of your money on known marketing tactics that work i.e. branding, direct marketing, SEO/PPC, email, mobile, etc... once you have tapped that out, then explore new areas like social media.