I have tab files (or shp) with information like residents , buildings etc... I need to be able to click a point in web map and query all data that fall in certain radius. I didn't decide yet which WMS I'll use because my web apps are .net and although geoserver seems more popular , I have zero experience with java. Let's say I chose a WMS. Should I use it's sdk (if it has any , currently using mapxtreme to query map data on server side) to query files directly or should I import all to SQL 2008 and work with it (not sure how to search within polygon or in radius yet) Tips , opinions will be welcome
WMS has a request called GetFeatureInfo that you can use and will give you the information you need.
To get this information you don't need any programming or using any SDK: on the client side just build a valid GetFeatureInfo request and send it to the WMS server; that is, you don't directly query the database or the shapefile. Both GeoServer and MapServer implement this WMS request.
About the data sources, a usual option consists on using shapefiles containing the information you mentioned - residents, buildings... - as attributes. Another options is using an spatial enabled database like PostGIS.
Last, choosing MapServer or GeoServer is a matter of taste. I have used both and I prefer the latter for many reasons. One of them is that I find that GeoServer is easier to install and configure, which is done using a web interface.