iMac screen spanning

Has anyone here tried this already?

I read this on http://www.macworld.com/weblogs/editors/2004/10/imacscreenspanning/index.php and really want to give it a go.

However, on the actual site of screen spanning doctor, http://www.rutemoeller.com/mp/ibook/supportlist_e.html it doesn’t specifically mention my iMac G5 type: a 17" iMac G5 1.8 GHz, combodrive, ATI Radeon 9600 128 MB

So I’m a little hesitant. Could I harm my machine by trying?