I have written about backing up your blog and have mentioned about using BlogCollector, unfortunately, I have tested BlogCollector on a blog using the New Blogger template, and it didn't work. So what is left now is:
1. to set your blog to send an email to a specially created email address to collect posts (unfortunately, this will not include the HTML that would display images, etc and also if it is an old blog, and you want the old post to be backed up, you will have to do it manually one by one)
2. Manual method. Open each post in the EDIT HTML mode, copy and paste the content into Notepad and save it somewhere safe and easily accessible.
3. Use HTTrack. I have tested using HTTrack and as I expected, it works for both blogs using old classic templates and New Blogger templates. I expected it to work because it mirrors Webpages which does not depend on how the Webpage was created. If you use HTTrack to backup your blog, you can even burn the mirrored site onto a CD and send it to other to view, etc.