[HibyPrime]

Free:

http://www.getpaint.net/

http://www.gimp.org/

Not so free (bootleg is free, however):

http://www.adobe.com/products/photoshop/

http://www.corel.com/servlet/Satelli...72554948&lc=en

http://www.adobe.com/products/fireworks/

I would reccomend Photoshop above all others, then probably GIMP.

Google tutorials for any of the above programs.