Recently a client wanted to change the content of the default blog post when a user creates a blog. There was some objectionable material in the existing text of the post. Without questioning this, the way to change that post's text is as follows and contributed by a venerable SharePoint Ranger!
Checkout the “C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\Resources\core.en-US.resx” file
It has the English (US) version of the text that you can modify (you’d have to do this on all WFE’s btw)…
To begin using your site, click <b>Create a Post</b> under Admin Links to the right.
<p><b>What is a Blog?</b></p4>
<p>A Blog is a site designed to help you share information. Blogs can be used as news sites, journals, diaries, team sites, and more. It is your place on the World Wide Web.</p>
<p>Blogs are typically displayed in reverse chronological order (newest entries first), and consist of frequent short postings. With this Blog, it is also possible for your site visitors to comment on your postings.</p>
<p>In business, Blogs can be used as a team communication tool. Keep team members in touch by providing a central place for links, relevant news, and even gossip.</p>