BackgroundColor Towns in a State on the Fly

[Tinker]

I’ve been struggling with finding an easy way to create a map to
display on a web page. My requirement is to have a map of
Massachusetts and to show all the towns (polygons) within
Massachusetts. Then I would background color each town on the fly,
based on some criteria. I was wondering if you might be so kind as to
offer any advice for the easiest way to accomplish this? I do have sql
server 2005 and asp.net web server. If I used a KML file for this, it
would be huge and then how would I color the towns on the fly?

Of course, the solution must be free, as the budget is non-existent !

Thanks so much !
Paul