How do I make my own Vista icon files from pics I have?

Question

It seems that all icons are 128x128 pixels square. I can work Photoshop CS3 well, and have created some of this size in hope that I'll be able to customize my files and folders. I've saved them in .gif, .jpg, and .bmp formats. However, I think I'm on the wrong path. Don't icon files have unique extensions (not typical image file types)? And can I simply rename it by that certain extension and put it directly to use?

What must I do?

Answer 1

yes,  ico but also you can use gif format