In increasing order of complexity :
Creating a choropleth map can be done very easily with Tableau. The visualization can be exported and made interactive. Tableau is not a free software, but you will have a trial period to try it.
We also had students implementing their choropleth map using D3 with the map imported using JSON. As far as I know, this didn't pose problems with IE, although I didn't specifically test them on IE.
Finally, the winning team in one of our course contest created a map (although not a choropleth, they still visualized data on it) using Processing. This usually involves more coding (Java-like), but doable and you can test their visualization on an IE8 browser (at this link - the visualization is very slow to load but this is more due to their extraction of tweeter feeds rather than the map itself).
In general, you can see our students' visualization at this URL, several of them having map visualizations - and you can browse technologies used for choropleth maps at the visualizing.org website.