In the past I've found open RTF files in Word Pad instead of Office enough to solve formating problems, but for a documents I was working on it wasn't enough. It was an old ebook I had on my palm pilot and was formated for a very small screen.
I tried finding and replacing all the "HARD RETURNS" like I use to be able to do in WORD PERFECT, but had no luck. So I decided maybe Open Office would let me find and replace hard returns.
Once again no luck, but what it did have was a "AUTO FORMAT"
Just highlight the entire ebook, click AUTO FORMAT and click Apply.
You can also click APPLY and edit but since this was a test, I just pointed and shoot, I figured anything would be better and it looks like it is.
If you don't have open office, it is free (but very very very LARGE).
300 Mbytes available disk space required.
http://www.openoffice.org/