PLEASE NOTE : jd-wp wordpress along with Open-SEF at this point in time (Jan 2008) have been left to languish by their developer.

Although there are several other contenders for the job the best recommendation we could give for a blog is to install WordPress in a sub-directory on your domain and make a menu link to it (url link)

Endeavor to make a new entry on your blog at least once a week using your site keywords in less formal/everyday comments about your subject/niche.

A blog invites interaction with your visitors and with regular posts can increase your SE rankings.