Crazy that people still try to solve this stuff by hand instead of leveraging a library like jQuery or Prototype. The Taconite plugin is my favourite way of dealing with this specific problem. http://malsup.com/jquery/taconite/
A valid point. Out of curiosity, what environment do you develop for that uses IE6/7 and has latency constraints? Is it a network performance problem, or just the parse speed of the library?