WordPress 3.0.2 has been released couple of days ago. The release fixes a security issue and some other bugs.
The security issue in the older versions of wordpress could allow author level users to gain further access on the blog. But even if you don’t have other users on your blog you should upgrade your blog to the latest version.
If your theme does not support the newer versions of wordpress you can hire me or any other wordpress developer to make your theme and plugins compatible with newer version of wordpress. But do not delay the update as you might later regret it and will have to hire someone to not only update your theme but also fixed your hacked blog or in worse case you might even lose all your precious data on your blog.
You can update automatically using the WordPress Dashboard of your blog or you can download the update and then do the manual upload. Once again if you are worried about breaking your blog you can hire me.
P.S I will soon write the step by step howto to update your wordpress installation to the latest version without breaking the blog.