As a general rule, security is set up on both ie and netscape to prevent you from keeping your source code hidden, however, there are some cases where you can hide it from the average user.
1. In IE, you can create a modal dialog box. This is like a popup window, and you can have HTML in it. No one is able to view the source code on this directly. Developers could still see the source code of the page if they are using a debugger like visual interdev(although it is also possible to use Microsoft Script Editor which is a scaled down version of Interdev which ship for free with MS Office). - Note: if you have hyperlinks in a modal dialog box, they will open in a separate window.
2. Other things you can do involve opening new windows without menus, and trapping the mouseclicks, so that you are directing what the user is able to do with them. Even so, the debugger I mentioned above, and many other tools out there would still allow someone to see your code.