You really do not need any software. It is kind of neat to see how AIM works using collumned paper. I have been using just paper since 1995. Tom uses Newport Software which produces most of the pretty pictures posted by him. You can get the web address from Tom's site.
Hi John and Welcome, I see you've already received one reply (while I was napping). Here's the page with some brief reviews: http://www.aim-users.com/aimware.htm
This isn't completely comprehensive, but will get you to many of the various vendors. Your choices range from what TooFuzzy said (long hand on 13 column paper) which is a great education, to software with lots of bells and whistles that go beyond the basic AIM equations.
Personally I have done it various ways over time. I started out with paper and pencil then switched to Lotus 123 (DOS) and later to a dos version of Newport. Still later when Newport was upgraded to being more Windows friendly (1995?) I switched to the newer version. I still use all three. Paper for teaching basics and to keep hard copy of transactions for some accounts, DOS Lotus for long histories and my Idiot Wave calcs and Newport. I've only had limited experience with AutomaticInvestor but mainly because I've been too lazy to get a working version downloaded. Same goes with Vortex and PCA. It's an old dog - new tricks thing.
I think there are fans of each product. Each seems to serve a specific need. For testing purposes the Excel template can be used if you're handy with such things. However, the software products with automated price history downloads make this easier. I'll let others chime in with their particular preferences.
Please feel free to ask questions as they come about.