I often see the Blogger domain of this blog and have a sinking feeling that I am stuck with this blogspot sub-domain. Believe me, there is nothing wrong in running your blog on a blogspot sub domain. There are instances of blogging successes on a blogspot domain too. It is just that with a custom domain and paid hosting, you have more flexibility and control over the various elements that comprise your blog. And for SEO benefits, it is advised to always run your blog on a custom domain - preferably using a blogging software like Wordpress - though Drupal would also make a good fit.
Today, I stumbled upon a very useful article written by Amit Agarwal which explains how to migrate your blog from blogger to paid Wordpress hosting and your own custom domain. What is relevant about this article is, Amit explains how to do the migration without losing any of the visitors to your old blog hosted on blogspot domain.
Check out Amit's article to learn how to do the search engine friendly switch of your blog from Blogger to Wordpress platform without losing any link juice.