This article is about a JavaScript-based PNG fix for Internet Explorer 5.5 and 6 on Windows. The fix allows IE to properly render PNG alpha transparency. Why only versions 5.5 & 6? Because Windows IE versions prior to 5.5 do not support the filter which fixes the PNG problem, and version 7 (not yet released at the time of writing in January 2006) is reported to have fixed the issue entirely.
Attachment contains everything you need.
Chinese explanations are also included in the zip file.
Reference: http://homepage.ntlworld.com/bobosola/