convert a .xls text file to a Valid Excel file

Is it possible for me to convert a .xls text file to a Valid Excel file through code?
I am using a text file with .xls extension which is basically a download from SAP.It does look like an Excel file. But it is not a valid excel file and it would let me connect to it using a connection string only after I open it manually in Excel and do a "save as " .
Can I do this process through code?
thx

If you are using VB, you can add a reference to the Microsoft Excel COM object. In VB.NET, you can download the Office Primary Interop Assemblies.