Showing Avatars

I have a sidebar on one of my Blog pages. One of the sections of the side bar is latest comments where we are showing the latest 5 comments for all the Blogs. One of the requirements is to show the Avatar of the person making the comment. I used this transformation:

<a href="<%# GetUserProfileURL(CurrentUser.UserName) %>"><img src="<%# GetUserAvatarImageUrl(CurrentUser.UserAvatarID, CurrentUser.UserID, 20, 20, 20) %>"

This does not work quite right because it returns the Avatar of the current user, not the necessarily the user to made the comment. What I need is for it to evaluate the CommentUserName so that it gets the correct Avatar for whoever posted the comment.

For example. I am the current user and I make a comment, but the next 4 comments were created by someone else. My Avatar should appear next to the top comment and the other 4 comments should have the avatars of whoever created them.

Any help would be appreciated.

Thanks.