Here are some software that can allow you protect your data:

1. PackPal Folder Locker
   
   PackPal Folder Locker is a password protected software which can encrypt your files, folders, pictures, drives, and documents in seconds.Protected files are hidden from kids, friends, colleagues and kept away from viruses, trojans, worms, spyware,and even networked PCs, cable users hackers. Even if you move the locked files from one PC to other devices, such as USB Flash Drives, Memery Sticks, CD-RW, floppies, and laptops. Files are protected securely on these removable devices as well.PackPal Folder Locker can encrypt or decrupt any number of files, folders, drives, pictures and documents in seconds.It works on Windows XP/2000/NT/Me and all kinds of disk types like FAT16, FAT32, NTFS.To use PackPal Folder Locker is the best method to guarantee that nobody accidentally or intentionally gets access to your private and confidential information.
2. File Securer software File Securer is a powerful tool designed to protect your sensitive folders and personal files. With strong security, File Securer embeds the protect into windows system kernel, both on command mode and window mode, all work professionally. With exceptional easy of use, File Securer let you be enabled to hide your folders and files any where. The locking and unlocking object function are integrated with system pop menu. It’s so easy, selecting object, clicking right button of the mouse, then clicking ‘lock’ or ‘unlock’, that’s all. If someone want to access you locked object, the system will say “Sir, give me you password please!”, and the tools will record all the error password and win-user, then report to you.
3. Folder Lock Folder Lock® is a fast data encryption and password protection software for Windows. It can simultaneously encrypt, lock and password protect your files, folders, drives, USB drives and even CD/DVD-RW.
   Folder Lock creates encrypted storages called ‘Lockers’. You can keep as many of your private files & folders in your Locker and password protect it with a single click. You can transfer, secure and backup these Lockers. Lockers are portable, you can keep them in USB Flash Drives, CD/DVD (R-RW), & notebooks or transfer them via email or upload. Lockers are even undeletable on the computer where Folder Lock is installed.
   You can treat Lockers just as you would treat them in physical world. Each user can have their own Locker. However, a single user can create multiple Lockers with different passwords as well. With Folder Lock, you can choose either to encrypt using 256-bit AES on-the-fly encryption or lock files, folders and drives anywhere on your computer. Each Locker can contain your encrypted files as well as your personal list of locked items.
   Furthermore, Folder Lock’s options like hack attempt monitoring, stealth mode, data shredding, history cleaning and auto protection can enhance data security beyond anything ever achieved. In addition, a locker’s delete, move and rename are password protected to prevent data loss.
   Folder Lock is Windows Vista / 2003 / XP / 2000 compatible and is the most downloaded File Security program in the market today.

1. Epocrates Rx (http://www.epocrates.com/). This regularly updated medication database’s free basic functions include adult and pediatric dosing, contraindications, adverse effects, pricing, formularies and more. Its multicheck function, allowing cross-checking of interactions among up to 30 medications, is especially useful. With yearly subscription upgrade, you will get a whole lot of features that are very useful for clinicians.
   For both Palm OS and Pocket PC.
2. MedMath (http://smi-web.stanford.edu/people/pcheng/medmath) – This application has collection of useful formulas in an easy-to-use interface. Another simialar application is MedCalc (http://medcalc.med-ia.net/). You can explore both site and see for yourself which is better.
   For both Palm OS and Pocket PC.
3. ATP III Cholesterol Management Tool (http://hin.nhlbi.nih.gov/atpiii/atp3palm.htm) – From the National Heart, Lung, and Blood Institute (NHLBI). This interactive guideline tool will assist the clinician in implementing the ATP III Cholesterol Guidelines at the point of care.
   For Palm OS only.
4. C-Tools (http://www.cancer.org/c-tools) – From the American Cancer Society, a timesaving PDA tool that provides instant access to cancer information to anyone in the healthcare field.
   For both Palm OS and Pocket PC.
5. Geriatrics at your Fingertips (http://www.geriatricsatyourfingertips.org/) - It is an excellent resource for those who care for older adults. It covers most of the common conditions present in elderly population and also includes assessment instruments, recommended diagnostic tests, management strategies, and both pharmacologic and non-pharmacologic therapies recommended specifically for older adults. Need to register at the site which is FREE.
   For both Palm OS and Pocket PC.
6. ACC Clinical Practice Guidelines (http://www.acc.org/clinical/palm_download.htm) – Concise, portable reference tool adapted from the ACC/AHA Practice Guidelines for the busy clinician.
   For both Palm OS and Pocket PC.
7. Johns Hopkins University Antibiotic Guide (http://hopkins-abxguide.org/download_center/download_center.cfm) – This is a regularly updated infectious disease guide. It features treatment guidelines, diagnostic criteria and comprehensive information about medications and organisms. Navigation is a bit cumbersome but once understood, it is easy.
   For Palm OS only.

To buy a PDA for medical purposes, you need to look at the following in this order:
1. Memory size. What is the internal memory size (RAM) of the PDA? For today software demands, it should be at least 64MB.
2. Expandability. It should have an option to expand the memory size – Memory stick or Smart Disk slot. This can go as big a 2GB which can store hundreds of textbooks, files, etc.
3. Size. This is based on how you would use it and your preference. But try to get screen that is bigger so that you can read the text easily.
4. Screen quality. Screen with enhanced colors (about 16 million colors) gives you the best quality when viewing images (dermatology pictures, family photos, etc.)
5. Processing Power. For general textbook viewing, this may not be as important. But if you also wants to run multimedia programs or software that require increased processing power, you may need higher end model (more expensive).

Here are some Palm OS PDAs, Pocket PC PDAs