As I also said, I really liked Audiocity, and will use it for my covering projects after my tests.
Also, thanks for Ap Tuner. I didn't know this one before and I usually just tuned my guitar by the ear with a devise that makes the right sound. By its description it sounds like I can tune a violin with it as well, which is just what I need :)
Another software that I think I remember someone put here already as well is the Tux Guitar, which enables you reading the GuitarPro tabs and other kidns of tabs you find online.. The link:
http://sourceforge.net/projects/tuxguitar/If any of you are familiar with a good and easy to use video editor software [which is not the Windows Movie Maker] or a tab writer software, I'd very much appreciate it :)