Glad it worked Viv. And to add Viv, sometimes transparent images do show up with a black background in VSD.
Back to Greg, yes I do believe the best idea is to do images for your headers, and to add alt tags for keywords if you want. Honestly though, you'll probably be repeating most of the text that in the headers in your page, so I would not be too concerned about it.
It's when people use text image for complete paragraphs that lose them their keywords.
gif, again I say, is more for animated images, and not sure why you're wanting them. Don't think WIS handles gifs, so if you want to lean that way, you'll have to use whatever program you used to make your Home page image - which yes, looks the best out of all your pages.