Very few people need Photoshop. It's powerful, but complicated. It takes for ever to open. It costs one bajizilion dollars. I only use a very small number of Photoshop's features, anyway. It is the personification of overkill.
Paint.NET is my image editor of choice. It allows you to create, edit and manipulate images. People often comment on the images that I come up with (like the header of this blog) - well they all come out of Paint.NET. It is a free program. It is a 1.5MB download. It is fantastic. Who needs Photoshop? Not me.
Paint.NET requires the Microsoft .NET framework (which you probably have already installed, esp. if you use any of Johnson's programs, e.g. SerialPref, HabitPref, Opa).