I finally found how to straighten a horizon in GIMP. I downloaded it onto a new laptop, as PS is on my desktop at home. As a free program its a good deal. Minor issues are when you open a jpeg the choices are shown in a list format, no thumbnails. And when saving an image the program selects some quality choice of its own that you have to override. And I have to find some method of handling RAW files.
But overall its as good as PSP X2 for sure.