Having tried out Wordpress on a cheap host the experience was just too slow so now moving back to Blogger. If for any reason you need to move from Wordpress to Blogger you will need to convert the XML export file.
For Small Blogs
Wordpress2Blogger web service provides a simple Wordpress to Blogger conversion. Login into your Wordpress blog then goto "Manage" or "Tools" tab and export your blog as an XML file.
Now upload the file to Wordpress2Blogger online service to make it Blogger compatible. Download the resultant file and import it into Blogger via the Blogger dashboard. Your Wordpress posts will be imported as drafts, from there you can check and publish then as necessary. This method works for export files up to 1Mb.
For Larger Blogs
Larger blogs require a different method. Take a look at the Google Blog Converter project. As pointed by Google OpenSource blog this new Open Source project provides the ability to easily move blog posts and comments from service to service. This initial release provides Python libraries and runnable scripts that convert between the export formats of Blogger, LiveJournal, MovableType, and WordPress.