Good question, Sean. There are three versions of Microsoft's Windows Mobile 5 operating system for handhelds: Pocket PC Edition, Pocket PC Phone Edition, and Smartphone Edition. Stand-alone PDAs, such as the Dell Axim X51 series and the HP iPaq rx1950, use Pocket PC Edition and come with the full Mobile Office suite, including Word Mobile, Excel Mobile, and PowerPoint Mobile. These handhelds typically have 240x320-pixel touch screens, can feature wireless connectivity, and are best for those who want a palm-size device to organize vital information with the option to work on the go and surf the Web.

Devices that run Pocket PC Phone Edition are similar to Pocket PC PDAs in shape and size (including the touch-screen functionality), with the full suite of office apps, but they add cellular-wireless capabilities so that you can make phone calls. These all-in-one mobiles are good for power users who need the full functionality of being able to work and stay connected on the road. Examples of Pocket PC phones are the Palm Treo 700w, the Sprint PPC-6700, and the Cingular 8125.

Windows Mobile 5 Smartphone Edition offers the biggest difference of the three versions. First, the mobiles are smaller, resembling cell phones, and they feature 240x320-pixel displays that aren't touch sensitive. Instead, you navigate via soft keys and a joystick. Also, while you get all the calendar and contact tools, you don't get the entire Office Mobile suite, just Outlook Mobile; third-party apps, such as Westtek's ClearVue Suite, are available so that you can view work documents. These types of smart phones are perfect for users who want the phone form factor but also want to stay up-to-date and be more productive on the road. If this sounds like you, check out the T-Mobile SDA or the Cingular 2125.