Hi,
First of all, leave off the (C)... it's unnecessary. All you really need is your name or URL. That's sufficient identification of your copyright ownership. I use my URL, so that people who "take" the image can find it again easily if and when they are ready to purchase, and so that I get "free advertising" when they post my "borrowed" images on Facebook, etc.
Use some software to create your own watermark out of a dark gray lettering with a fairly strong white outline, in a relatively bold font. Save it as a PNG file so you can have a transparent background.
Gray lettering with white outline works best on a wide variety of backgrounds. Otherwise you would need to create a light colored watermark for use on darker images, and a dark toned one for use on lighter images.
I put the watermark across the bottom third of my images, large enough so that not much is left if it's cropped off, but not too large to intrude upon the image.
Just keep to 400x600 uploads at the largest, so that files are too small for printing. If you standardize on a size, you only need to set up one watermark to use with it. If you have a lot of different sizes, you might need different watermarks (Note: some softwares, such as Lightroom 3, will automatically scale a watermark to fit different size files).
