To Create an Excel File in an ASP Net Web Site Go from this steps First of all you have to nvoke the "Stringwriter" and "HtmlTextwriter" classes. The following code creates variables for these classes:
Dim sw As New System.IO.StringWriter()
Dim tw As New System.Web.UI.HtmlTextWriter(sw)
Then Step 2 is:
Write some text to the textwriter variable. This text is displayed in the Excel file. In this example, a header is printed to the first Excel cell. The code below writes to the textwriter variable:
tw.WriteLine("<b> My Excel File </b>")

Then move to Step 3:
Place the header for the output. The response header tells the browser what type of file is displayed on the Web page, and the program used to open it. The following code directs the user's browser to open the file with Excel:
Response.ContentType = "application/vnd.ms-excel"

Then Step 4:
Display the Excel file to the user. The following code opens the Excel spreadsheet in the browser:
Response.Write(tw.ToString())
The user can view the page only or click the "Save" button to save the file to the hard drive.

Your Excel File have been created....

try the Grid View..

it will provide better performance then the spreadsheet !!