[Leslie]

http://www.mobipocket.com/en/DownloadSoft/default.asp?Language=EN

Can I also read e-books with Mobisoft Creator, or do I need to download both?

You need the Mobipocket reader to read ebooks. You won't be able to read your Kindle books using it, however. You can only read those on a Kindle.

I'd like to get Creator so I can convert some of the online newsletters I subscribe to into Kindle format. Does Creator have other uses beyond the obvious?

That would be the way to do it. I think Creator pretty much does one thing: create .prc files from other documents (Word, PDF, etc.)

BTW, are these even the best programs, or are there better options available?

These are the only ones I've heard people talk about and the price is right (free). For Mac users, there is Stanza which apparently doesn't have quite as many features as Creator, but it does the job.

L