A few things to consider...
You should always start out with your own domain name, regardless of what you are developing or where you are hosting it. That way all of the acquired backlinks and pagerank are *yours* - no matter what changes you might make in the future.
Blogger has been known to 'drop' accounts, meaning entire blogs just disappear. Sometimes for good reason, sometimes unknown. To be safe, it's better to control the content and database and control your backups.
You wont have detailed stats with a Blogger account. Your best bet is a third party solution. If you host your own Wordpress blog on your own domain name, you will generally have cpanel and awstats - which helps you to track your progress, see when your pages were spidered, and find out what search terms people are using to find your pages. Stats are invaluable to site growth.
Wordpress automatically notifies you anytime someone links to you or blogrolls you - and anytime someone blogs about one of your blog posts. Blogger doesnt. This is a VERY handy tool. There might be plugins and utilities (I'm assuming) to help those on Blogger to do tagging, trackbacks, pinging, etc... but it's all automatic with Wordpress.
It is a well known fact that frequently updated blogs stand to rank better and get more traffic. With Wordpress you can sit down once a week and write 7-20 posts, and then schedule them to automatically publish at certain times and on certain days. With Blogger you have to be in front of your computer to publish a post.
Here's what I do:
I get hosting for under $10/month that allows me to host up to 50 domains. Using Cpanel (included) I can install Wordpress with a couple of clicks. So for under 20 bucks and $10/mo... I'm in business - and in full control.
For each blog that you set up on Wordpress, you can also set up an associated account at Blogger.com. Use a related username and create an introductory post that tells who you are, where you blog (link to your wordpress blog) and what your objective is (or a compelling description of your blog and its purpose).
You'll need this blogger account to post comments on other blogs that use blogger (those that require you to log in before you can comment). Since you will be using Social Networking to grow your own blog, this is a great way to send people from blogger to your "real blog"
