Open SharePoint 2010 Document Library Files Programmatically

Hi,

I have a Visual WebPart, which has a ASP.NET GridView and the GridView display all the files present in a SharePoint 2010 document library.  The Gird has a LinkButton and when user clicks the Linkbutton I want that file to open.

The document library may have different formats like, Doc, xls, pdf, for any image format.  Can some one help me with this.  I found some blogs online which tells how to open specific formats like Doc or xls.

I want to be able to open any format, and if unable to open then should give an option to download.

Also, if it is doc or xls format, I want the user to be able to edit the file and save it back to the document library.

Thanks, 

Regards, Vikram