Can anyone suggest a program that enables one to show pictures on
one's web page as a FULL SCREEN slideshow? (Microsoft's Power Toys for
XP includes a HTML Slide Show Wizard, but the pictures on the web are
not displayed full screen  - pressing F11 helps, but the pictures
themselves are still not full screen).

mahalonui-ga

This will answer your needs:

http://gallery.menalto.com/

To quote from their own feature page:

http://gallery.menalto.com/features

"Fit-to-window Images[0] - If a visitor has a supported browser,
Gallery can dynamically resize images to make them as large as
possible while still fitting inside of the visitors browser window."

affordablemagic-ga

Not what you want to hear, but NO.  The images can only be as large as
the browser window, but no larger. Most newer browsers do not allow
popups that hide the title bar, so you'll always have the window
border, title and status bars.

I'm afraid that a web site (for obvious security reasons) could not
'force' user to do anything on their remote computer.

You may want to combine the above with the use of the full-screen key
(and include that instruction on your web page) e.g., in IE / Mozilla
press F11.

affordablemagic-ga

Irfan View (Hands down)