Finally I decided to set up a plugin for images in the posts. After searching the web for a different variations of plugins I stopped on ImageManager.
Actually, most of the plugins were good, but the problem with me is that I have an old GD library and ImageMagick is somehow not working very well :(
ImageManager allows to choose between GD,ImageMagick and NetPBM for manipulating graphics and NetPBM seems to work fine in my case.
In addition to above, I liked the GUI of the plugin. It replaces the img button in the post area and provides with a nice popup where one can see/organize/edit/upload images.