set report name and content type

Using Crystal Reports 2011

Visual Studio 2012 with CR for VS 13.0.5 in C#

issuing the following:

m = (System.IO.MemoryStream)theReport.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
this.Response.ContentType = "Application/pdf";
this.Response.BinaryWrite(m.ToArray());

auto opens the report in PDF format in the browser..

but if the user clicks save the report name is the name of the aspx file..

so that I can specify the report name I added a header:

m = (System.IO.MemoryStream)theReport.ExportToStream(CrystalDecisions.Shared.ExportFormatType.PortableDocFormat);
this.Response.ContentType = "Application/pdf";
this.Response.AddHeader("Content-Disposition", "attachment; filename=" + sAttachment + ".pdf");
this.Response.BinaryWrite(m.ToArray());

this does set the reportname to what I want, however, the PDF no longer opens automatically, the user is prompted to OPEN or SAVE..

is it possible to set the report name and have it auto open in the browser.