Well I would suggest something pager capable if she is a doctor, perhaps one of the new Treo 650's. You can always get the medical software later. I do not think any Palm OS device is geared specifically towards those in the medical field, but there are plenty of freeware and shareware medical applications out there. One resource would be Freewarepalm.com
As far as the quality of the device is concerned, my Treo 600 is nearing its one year birthday without a replacement. I have had no problems with my 600. Another resource for the Treo device would be Treocentral.com If you don't want a smartphone then howardforums.com will be able to direct you to a solution.