recently just moved from PHP to asp, and I know that in PHP I could write a switch to include files and save it as a php file. When i wanted a page i would just change the id at the end of the url. In the example below, whatever.php?id=1 would display mypage1.php. My question is how does one do this in ASP. I think its possible.

ie.
switch($_GET['id']){

case "page1":
include("mypage1.php");
break;
case "page2":
include("mypage2.php");
break;
case "page3":
include("mypage3.php");
break;

Use a select ... case ... construct

<%
select case lcase(request.querystring("id"))
case "page1"
%>
<!--#include virtual="/page1.asp"-->
<%
case "page2"
%>
<!--#include virtual="/page2.asp" -->
<%
case "page3"
%>
<!--#include virtual="/page3.asp" -->
<%
case else
' this will be executed if no querystring value exists or does not match
%>
<!--#include virtual="/page.asp" -->
<%
end select
%>

Be aware that in ASP includes are parsed before code execution, so if any variable names are duplicated in any of the includes it will throw an error. Common variables should be defined prior to the select statements.
If this creates a problem look at using the server.transfer("page.asp") method in place of the includes.