Carl, you also need to try to find out how they got in. your admin user name and password may have been compromised. You should certainly consider changing your admin password immediatly, and choose a strong passowrd of at least six random characters that is hard to guess. There are articles in the CODEX and other places that address WordPress security which will help you harden your installation. Many of the things you can do don't require any coding.
The file I am talking about is in your theme, and it appears that you are using the Default theme. You can log in to admin and use your Theme Editor (Under Design) to look at the code. If you prefer to pull down a copy with FTP and look at it, it should be at:
If you have not made any modifications to the Default theme, you might be able to get rid of the hack by re-loading the theme.
Good luck with this.