When you have decide you would like to start a blog, you have two options to go with, use a free host such as WordPress.com, or decided to buy a domain and hosting from a provider and host a standalone version of WordPress from WordPress.org.
Some of you may choose the cheaper option, and head on over to WordPress.com and signup for a blog there, the defaulting domain is http://yourname.wordpress.com, you can choose to stick with this for awhile, or you can purchase your own domain name, and then purchase upgrades from Automattic to have your domain name mapped to the WordPress.com domain. This is useful if you would rather have the Automattic Team handle your hosting, and server upgrades, and WordPress upgrades. However, if you decide that you would rather handle all of these issues yourself, you should be looking at hosting your own installation of WordPress.
The first and most important step is to ensure that you find a host suitable to host WordPress, and that your domain is pointing towards the correct nameservers so that you can access the site once it is required.
Once you know that the domain is working correctly, install WordPress on your webhost, and run the install to make sure that it is working correctly. Once you know that it is working correctly, we can then proceed to the backing up of the existing blog.
Login to your WordPress.com account, and in the control panel go to Tools -> Export. You can choose which authors you wish to include, or all of them from the drop down list. Once you have done that, click on the "Download Export File", and save the file to your computer or flash drive.
Head on over to the control panel of the self-hosted WordPress installation, and log in. Head to Tools -> Import, then select "WordPress" from the bottom of the list. Click the link and you will be presented with an upload box, enter the file name and its location into the box either by typing it in, or using the "Browse" button, and select the file. Click the "Upload file and import" button, and WordPress will start uploading the XML file that you downloaded from your WordPress.com blog.
The next screen allows you to assign the posts to an existing or new user on your WordPress installation, choose the user, or create a new username. If you have uploaded files to your WordPress.com blog, ensure you have selected the checkbox to copy the files across to your webhost provider to ensure that your files will be available. Remember though that you will need to update image locations if you used absolute referencing for your images.
Once you click on the link, WordPress will display the details of the posts and files as they have been copied over to your installation of WordPress. You may need to delete or edit the initial post provided by the WordPress installation if it appears out of sequence.
Please feel free to contact us via email (andrew [at] wpthoughts.com) if you would like clarification about the process, or need any help at all.
This post was inspired by ProBlogger.

January 12th, 2009 at 9:17 am
This was very helpful!
Thank you!
January 21st, 2009 at 5:07 pm
Hey AWESOME blog, added to my top 5 favorites