Well, had the same challenge, but I 'solved' it in a different way.
I simply removed the fixed dimensions (in topic.asp) and approve/reject avatars upon upload.
I've inserted a blank avatar, called noavatar.gif, and use this code to replace a non-assigned avatar :if Member_Avatar <> strImageURL & "noavatar.gif" or Member_Avatar <> "" then
Response.Write "<img src=""" & STRFORUMURL & Member_Avatar & """ border=""" & intAvatarBorder & """>"
end if
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