You're starting out. You need a web presence. Facebook is easy - why not just use that?
There are some things to be said for Facebook (or any of the other hundreds of social media sites). They're free to start. They're fairly easy to update. And yes, you should be using them - but as a feeder for a website. Here's why.
1. You hand out your business card. It has your email address on it. It's email@example.com - it's quite natural then for people to expect to visit your Oxford Web Business at that address. You could of course forward this address to your social media page, but you probably shouldn't. Because,
2. People who've met you are evaluating your business. They expect to come to your web presence and see you there. Branded as you. Not branded as Facebook or My Space. That's because your brand is important and you don't want it muddied by someone elses. You want to be in control.
3. You're not really in control of your social media presence. That's by design. Social media is all about interaction and sharing. Sharing good comments and bad. Once you have a social media page you will have to deal with negative comments. One customer we know, when you visit their Facebook page, had as the top three items: a very negative review of them (which they had responded to), a blog item by them and then a spam item pointing users off to another Facebook page on how to earn cash quickly. It takes work to continuously bury the bad and spam.
4. It's not that easy to optimise your Facebook or Twitter pages for your key words. You can't point search engine submissions to that page, you can't effectively use titles and links and you can't control how much content is on the page. So - whilst a social media presence is useful and important, a website is too. You need one to build and manage your brand and marketing communications. You need one where your content is king and develops over time. And whilst there is a cost to a website, it's not that much.
As we get bigger sites and more complex management, we've been investigating (and using) an automated site management tool called Aegir. It has mainly been used in house for managing our development server, but now we have rolled our first site out on it in production.