Photo editting software

What do you use to edit your photos?
Free or not?

I'm currently taking a photography class and having a editting software is required. I'm crammed for money right now. I do have Photoshop 7, but I can't download it on my computer thanks to losing the box with the code on it.

Do you like the software you use? Pros? Cons?

Thanks ladies!

free software I prefer Pixlr.com
I use CS5 at work.

I use Gimp, it's free from http://www.gimp.org

You can download gimp! It's free and I love it.

I use photoshop cs4, and i know cs2 was being given away for free... jsut can't remember the link