There are two major operating systems for PDAs – Palm OS from PalmSource and Microsoft’s Windows Mobile (formerly Pocket PC). PDAs that run on Windows Mobile are commonly referred to as Pocket PCs and those that run on Palm OS – Palm PDAs. Although Microsoft does not make the hardware for the PDAs that run on its operating system, they do license the software to a variety of vendors. As a result, Pocket PCs are made by companies like Hewlett Packard, Viewsonic, Dell and Casio. Palm Inc. makes its own PDAs and licenses the software to Handspring, Visor and Sony as well.

There are a couple of things you should consider before choosing one of the operating systems:

1. Ease of use
Palm PDAs are popular among users with their ease of use and simplicity. The interface is quite intuitive and tasks can be performed with a minimum number of taps with the stylus (the pen-like instrument for controlling a PDA). On the other hand, the Windows Mobile OS is a bit complicated and has a little bit steeper learning curve.

2. Data input methods
There are several ways you can input data into a PDA:

• via a built-in QWERTY keyboard by using your thumbs
• via a virtual on-screen keyboard by tapping the characters with your stylus
• via a handwriting recognition system that can translate what you write on the screen with your stylus
• and via a built-in voice recorder.

You can find virtual and QWERTY keyboards on both Pocket PCs and Palm PDAs. However, there are some major differences when it comes to the handwriting recognition systems that each OS employs.

Palm devices rely on a method called Graffiti to translate handwritten text. You have to write characters in a specific way in a designated input area at the bottom of the screen. Many of the letters resemble the actual alphabet but others are quite different. Thus, Graffiti is very accurate but also a bit challenging to learn. Fortunately, newer Palm PDAs come with an updated version of the method, Graffiti 2.0, which is easier to master.

Windows Mobile offers three different handwriting recognition systems. One of the most popular is the Letter Recognizer that’s based on a method called Jot (the same technology used by Graffiti 2.0). The other option, the Block Recognizer, is based on the original Graffiti method. And third, you can use the Transcriber that is able to translate both printed and cursive handwriting and allows you to write anywhere on the screen.

As to the voice recorder, it comes in handy for taking short voice memos. Note, however, that only a few Palm OS devices have built-in voice recorders whereas all Pocket PCs support this feature.

3. Synchronization and Microsoft Office compatibility
Synchronization is the process of exchanging data between two or more devices in order to have the same information on all of the devices. For a PDA, synchronization with a desktop/laptop computer is of paramount importance.

Palm devices are well known for their flawless synchronization software – HotSync. It is compatible with both Macintosh and Windows PCs and allows you to synchronize with Microsoft Outlook or Palm Desktop. Although Palm OS PDAs do not come with out-of-the-box support for Microsoft Office documents, you can get a third-party solution such as DataViz\'s Documents To Go. Many new models even come bundled with it - otherwise it’ll cost you around $30.

Pocket PC’s use ActiveSync for synchronization. Unfortunately, it seems to give many people problems. One thing is that you\'ll need additional software in order to synchronize between a Pocket PC and an Apple-based computer. Pocket PCs come with scaled-down versions of Microsoft Word and Excel (Pocket Word and Pocket Excel). However, Office documents lose some formatting when transferred between the Pocket versions and the desktop versions of the programs.

4. Available third-party software
When it comes to third-party applications, Palm OS definitely has an advantage over Windows Mobile. Pocket PC users can find a few thousand applications for their PDAs. As a comparison, Palm OS users benefit a library of around 30 000 third-party applications, which means more potential functionality.