Generating excel files on IIS based on ASP.NET Form input

See more:

C#

ASP.NET

IIS

Hello guys,
I am trying to build a site where used has several text boxes for input and after these boxes are filled with text and a button is pressed I need specific excel/word file to be generated and sent vie e-mail.
Everything seems to be easy, except.... The only way out I know would be to use Microsoft.Interop class, but this would require the user to have MS Office installed, which a mayor problem here.
Does anyone know a better way out of this?

P.S.: the files should be xlsx and docx (the newer format).

Thanks in advance!