First of all don't forget as limited as it is, if you're using windows you have the Free Paint app, which can do allot of things from adding borders, text, touch up, erase, etc.
Also if you have any of the free MS Works from 5 forward which tend to come bundled with PCs and Laptops, they have versions of Publisher within them which are quite good.
Then I agree that Gimp is quite good and I use as well but if you open a Free Photo Bucket On line acct. it now comes with a very nice and user friendly editing app.
Finally, Windows 7 comes bundled with the Snipping tool which can be very helpful in capturing just portions of pics or photos you want and it even has limited editing capabilities.
I hope this helps.