Actually Goody, what you should be doing is not starting all over again with a fresh install but rather, upgrading
Basically create a Blog folder on your portable brain, copy over all the contents of your current Blog folder and then install Blog from the latest beta onto the same folder (the one on the portable brain :p) It will prompt you to upgrade when you first run Blog and after that, you should have your old blog entries with a new Blog install.
The other option, since you already have a new Blog install, is to take a backup on your old Blog install, and then extract the contents of the backup ZIP file into your new Blog folder (while Blog is not running). After that, when you first run Blog, it will prompt you again to upgrade. Simply go through the process, Blog might not work correctly after the upgrade. In that case, simply quit and come back in (that bug is fixed in the latest beta which has not yet been released.)