Copyrighting is a different beast then it used to be. The internet has changed the way we look at copyright and the idea of ownership. Arguably when you digitize something (music, books, tv) putting it into the ocean that is the internet, that new digital something, becomes a shared part of the whole internet collective.
Does that make sense?
I am not saying that I agree with that opinion, but it does hold some weight. The internet is a shared system of information. When you add to the collective the collective becomes richer because of your contribution. If your contribution is of significant value (a great song, book, etc) you get richer too.
So if you digitize a song and it becomes popular you do run the risk of someone stealing it.
BUT in today’s world there are a shat load of bands on Myspace (literally millions) and your biggest problem is not going to be someone stealing your melody lines. Your biggest problem is getting someone to even LISTEN to your melody lines. If you do write Viva la Vida and Coldplay comes and rips it off consider yourself lucky. Most bands won’t even reach that level of fame.
That does not mean that you should forever go without copyrighting your songs.
If you have the money, and you have quality material, then go for it.
But for up and coming bands with little money and a modest fan base the idea that you should copyright your songs because they are so good, and Bon Jovi totally needs a new sound, and he’s coming to steal your genius lyrical hook is pretty, pretty, pretty, pretty unlikely.
Save you money kids. Demo your songs, practice your craft, and soon enough you’ll be dealing with the headache that can be copyrighting your songs.