KML into MySQL or PostGIS

A relatively straightforward requirement... 1. Create a polygon in Google Earth eg a rectangle, pentagon etc, and save as KML. 2. Import the KML polygon into MySQL (or PostGIS) as a spatial object and index (R-tree?). 3. For a series of lat/long points determine if the points are within the polygon by using spatial queries. We would like this to run from a browser, but may require server side processing? Also we would like the polygon stored in the database to be shown on Google Maps with a transparent fill, say red. MySQL v5.5 is our preference but we are open to using PostGIS if this is easier/better. Please advise your recommendation as to the database.