Well, there is probably some software here to help convert those txt files.
I myself got the Kindle, and LOVE it! But I spent 10-15 years reading on my Palm pda, until my eyes began telling me to Stop It! The Kindle is far easier on eyes, if yours ever complain to you.
Welcome! Do take note of the link for "EBooks" on the blue bar near the top of the page. (I didn't see it for a while). There are loads of older books formatted for Mobipocket. Enjoy!