An excellent repository of opensource software, web applications, content management systems, design tools etc. etc. Visit Source Forge http://sf.net
Using the combination of Fireworks and Dreamweaver are really your best bet for managing 5 websites. I realize it doesn't answer the 'free' question, but the small investment in these two software tools will make your projects easier to manage. Because Dreamweaver and Fireworks are integrated it really does help in terms of design, code and content revisioning. Combinations of free html editors and graphic editors, like the GIMP, will not give you this degree of "compatibility".
On a side note, in terms of content images, if you want a quick editor, visit PICNIK
. We teach our clients to use PICNIK
when adding small images into their content managed websites.