There are several sites out there that allow for FREE PDA medical downloads.
1. www.epocrates.com
2. http://www.freeware-palm.com/tag-medical.html
And this is my favorite site with the most to offer!!!!
http://www.rnpalm.com/software_palm.htm
I hope this helps in your quest! I have a PALM m30 and got all my software from the sites above. When I upgrade to the PALM Centro Smartphone next month, I'll be revisiting the sites for software once again!