There's a student version of Lertap 5, a total freebie. It's limited to processing no more than 44 data records, but has no other limitations. This version might be a good one to download even if you're not a student -- it demonstrates what Lertap can do.
A 2-megabyte Zip file with the student version, the help file, and installation notes may be obtained from our main website at www.lertap.curtin.edu.au (once there, go to the Software page).