May I very strongly point out that using the 'open window notifier' thing is extremely unreliable, as MattyRid already explained. Also see:
http://shoutbox.menthix.net/showthread.php?tid=69...d=769629#pid769629
Using this will not
aid older people at all!!! In fact it will confuse them even more as it is not consistant and not reliable at all.
Instead, what you should be looking for is setting a decent sound for when a message is recieved, turning up the volume, enlarging the taskbar or even enlarging the size of the GUI windows and controls in Windows itself.
I suggest to use real solutions and not some half-baked dodgy methods which don't work anyways (not to mention you need to know how to install, use and understand them, etc... which even computer-literate people aren't always able to do!!)...
/ 
