You don't need to make a big fancy site to start you just want to get the best name possible before someone else gets it.
The key is to just get a domain name and stick with it, use it and promote it. This way when you give information to someone they are going to your address not someone else's. Once someone links to the "wrong" page for you it's really really hard to get them to start using the address you want. You need to make sure from day one that your address is the correct one. Plus the more they link to your address the more it helps you with search engine results.
As a minimum I really recommend you have a "splash page" that has a little information and then has some links to other sites you are using or refer to you (photos, myspace, GarageBand, any other social networking sites, reviews, newspaper/web mentions of you etc.). Sort of like a mini press kit. When you publish your address, use these web address tips.
Worst case scenario you can redirect your domain name (web address) to some other page on the net (like your MySpace page).
You might even be able to get an e-mail address at the same time you register your domain name. And have your address be something like me@mymusicsite.com
Then go submit it to the search engines.