I have had a look and haven't yet found any actually free flash tools, but there are a few which offer a free trial period. That means you can get it and work for a few days to get what you want done and deploy it. Of course they may watermark such a piece until you pay for the software, I haven't tested any of them.
Flypaper looks like it might be quite functional, I know the Adobe Flash product is incredibly powerful, but can take a while to get your head around. Also say SWiSH, which is a lot cheaper than other tools, so may be a lot less powerful, but you don't need a lot of power for what you're planning.
If you find any of these which work for you then I would create the text in the shape you want it to appear, then set a number of flat colour rectangles above each word and over the timeline have each one fade out, showing each word in the order you require. if you wanted to go further you could turn each word into an image and have it appear, flying in from the sides or coallescing from huge down to it's end position. Just a few ideas, the possibilities are endless with a little creativity
Oh, just found this, it may work:
It looks very simple, I haven't had time to actually test it, but it's free and may have what you need (since you're looking for graphics, not interactivity, which the big flash tools offer)
~Ben
Occasional sparks in a darkened room