Yes, Lacie is right, you only need 25 "Likes" to claim your unique URL by going to http://facebook.com/username
Also, if you don't have a unique URL yet, here is a good way to get the URL for your page:
Go to your page,
Click Refresh for your Browser,
This is the link you need. It should look something like this:
"http://facebook.com/pages/yourpagetitle/1234556676" or it might look like this:
It should not have the word "profile" or "ref" or "referral" in it.