Go to Google click here and run this as your search:
disable IE image toolbar
You'll get moe returns than you could ever hope to want.
Before you do though, be advised that you are completely wasting your time.
The only safe way to protect images from copyright theft on the web is to not display them. The next best solution, if you have to display them, is to watermak them.
Any disable right click scripts depend on the web browser (Opera is immune to them and totally ignores them) and uploading a transparent GIF to cover your main image won't stop anyone from raiding the copy of your image(s) in their temporary internet file cache, whcih holds a copy of every file you look at online.
Without paying serious money for various protection systems that are way beyond the limits of most domestic and small to medium businesses you are largely wasting your time.
Image theft is rife online. Anything you offer for diaply must be watermarked or you have to accept that people can and may swipe it. It's as simple as that.
Good luck with the script though.