some kind of basic Windows software that came with Windows 7.
That wouldn’t be Windows Live Photo Gallery would it? If so, you could try that! (If not, you can get it here. [Scroll down and click on the appropriate language to download it.]) I used to always shoot in jpg and use WLPG to “edit” my pictures. I don’t really recommend that any more, (it wastes a lot of HDD space) but in a pinch it could come in handy. If you need some more detailed instructions, just let me know, and I’ll see what I can do. Perhaps you could post an example shot that we I could use to make a tutorial, if you’d like.
It’s definitely possible to use GIMP for that task, although it would likely take a lot more work. If you’re doing it for a large collection of pictures, I would definitely try WLPG first and see if it is satisfactory.