Yes of course; it's trivial to "steal" (ie copy to your hard drive) any image in a web page. The practice of disabling the right click is completely pointless, and just infuriates users - don't do it.
To get an image you don't even need to do anything vaguely hacky like Ctrl-U: you can just take a screenshot of your desktop. Pop open your favourite image editor and crop it: job done.
The best way to protect images on the web is to a) watermark them b) have them in low res.
But the general point is: if it renders to your screen it can be copied.
