Here is the case. I have up and running database on MSSQL server. My client deliver me updates. Since now they were as INSERT statements, but they decided to change some stuff at their side. Now the updates will come as pairs of files (.dbf and .mdx) for each table...
The DBF / MDX extensions imply dBase formatted files to me.
You should be able to browse the file using MS-Access, and/or create a linked server from MS-SQL using sp_addlinkedserver and treating the DBF file as a dBase or FoxPro file.
Once you are able to view the files, you'll need to figure out what they represent. They could contain the rows added, changed, both added and changed, and possibly deleted. After you figure that out, then you'll need to process those rows according to whatever they represent.