[coderzone]

Whenever we change the names of any files on webserver its better to make a 301 permanent redirect from the old URL to the new URL and for Linux server you can use the .htaccess to make the permanent redirect. I find a disadvantage of this as it is very much dependent on the OS of the server and if you are changing hosts then there could be a problem of old URL not being redirected and so its better to put the redirection into the code. Here are the code snippets to achive the same.
PHP

<?
  Header( "HTTP/1.1 301 Moved Permanently" );
  Header( "Location: http://www.newdomain.com" );
?>

[aspguy]

In ASP.NET

<script runat="server">
private void Page_Load(object sender, System.EventArgs e)
{
  Response.Status = "301 Moved Permanently";
  Response.AddHeader("Location","http://www.newdomain.com/");
}
</script>

and in ASP

Response.Clear
Response.Status = 301
Response.AddHeader "Location", "newUserLogin.asp"
Response.Flush
Response.End

[jspguy]

response.sendError(response.SC_MOVED_PERMANENTLY, "/newURL.jsp");

[shabbir]

Edited title of asp redirect and jsp redirect post.