In many cases your Bio should be brief and to the point, a couple of paragraph’s is plenty in many cases. Most people who go onto pages like your MySpace page won’t read much more than that. If they want more they can read your blog.
Most people don’t really care where you were born, went to school and one a talent quest when you were 11. Tell them about your music style, your genre, what you think will make them want to know more about you and listen to your music. Tell them what you have achieved and what you have to offer. Think WIIFM (What’s In In For Me) Your Bio should be short and punchy.
At the end of your bio you can always have a note of where to contact you or get more information.
Make your Bio fit for it’s purpose. You could end up with several of them.