Haloscan
Haloscan is an easy to install and use commenting system, a great advantage of it is that it doesn't require PHP and it's extremely lightweight. Just go to www.haloscan.com and click on 'Sign Up Now', then fill in your details, get your username and password and they will send you an email with your account information aswell.
Once you have done that and logged on, click on Install near the top, it's below the 'Signup' link.
Now you will be on this page with lots of tickboxes. Choose the None of the Above/Manual option and untick the 'Display trackback code' and 'Display rating stars' (these are something you don't need).
Click Next, and you will be with on a page with a few codes, the coding below 'Step 1' should be placed on your Index page's coding, if your using iframes then put the 'Step 1' code on top of your blog pages coding. This first code is to implement Haloscan onto your webpage and is needed on a page where you wish to place a commenting link.
The second code, is the code that provides a link to your commenting system (haloscan). So copy this 'Step 2' code to wherever you want the comment link to appear, possibly near the beginning or end of a blog.
Having more Haloscan Comment Boxes
If you want to make different commenting box links, for different blog posts. Then whenever you install the second coding for a different blog just replace the word 'Name' in the coding with whatever you want such as a number signifying the date (blog23082007 meaning 23/08/2007). Now only that link will up another haloscan commenting box different from a previous haloscan which is in another post.