Welcome to MAS Shiela :D Perhaps PSP7 hasn't got a straighten tool - I was using another version. I don't see anything wrong with straightening images the way you are doing - it works and that is that. Your image above is straight [as I said], I'm sorry I dropped it and bent the frame :D

And every one said, 'If we only live,
We too will go to sea in a Sieve,---
To the hills of the Chankly Bore!'
Far and few, far and few, Are the lands where the Jumblies live;
Their heads are green, and their hands are blue, And they went to sea in a Sieve.

Edward Lear
http://www.nonsenselit.org/Lear/ns/jumblies.html