I had a quick look at the three example and all seem to use javascript.
The first two use swapimage to change images on hover and the last one uses onfocus="blur()" which does much the same thing.
There's no Flash as far as I can see.
To get a fluid design that adjusts to users' browser resolution, use % widths for everything - divs, side margins, side padding, side borders and even image widths.
To prevent your page being much too wide at say 1920px window width or completely squashed up at 500px width, use max-width and min-width. This doesn't work in old browsers like IE6 so you probably need a conditional comment and use a fixed width just for IE6.
See http://www.webdevforums.com/showthread.php?t=28044
Code downloaded to my PC will be deleted in due course.
WIN7; IE9, Firefox, Opera, Chrome and Safari for Windows; screen resolution usually 1366*768.
Also IE6 on W98 with 800*600 and IE8 on Vista 1440*900.