CR Data Field Mapping

I am looking for .Net solution to perform field-to-field data mapping from my user files into our standard set of fields. Users upload files to our site and the field structures of these files vary greatly. This solution should be delivered in a form that I may integrate into our website. It requires users to easily map the fields in their files (delimited files and excel worksheets) and assign them to approximately 30-40 fields that we use on our site. The solution should comprise a display of the client records so that the client can see their actual data as they appear in the upload file and easily assign their data fields to our set of fields. Source and target data should be displayed in side by side grids. Once the field mapping is complete, the application will store this mapping metadata information in our sql server database so that clients can recall the mapping scheme and use it next time they send us a file. Additionally, application must permit clients to use the mapping(s) they have already created so as to transfer their data into our sqlserver table without need to remap.