Other Hardware Differences
In addition to input and output, there other hardware differences on a Pocket PC. First, the CPU is much slower and doesn't have a floating-point processor. I've heard that the processor in an average PDA is roughly equivalent to a 100 MHz Pentium. The memory in a PDA is also measured in 1990s terms. A typical Pocket PC comes with 64 MB of memory. And because these devices don't have a hard disk (not yet, anyway), that memory has to store both the programs and all the application data.
Most PDAs do allow additionally memory by using an external memory card, which brings up another difference: hardware expansion. All kinds of gadgets can be connected to a Pocket PC using special sleeves, CF (Compact Flash), or SD (Secure Digital) cards, but the rub is that you can use one at a time (sometimes two, depending on the PDA model). This is a limitation to keep in mind until vendors start shipping all-in-one camera, GPS, WiFi, barcode scanner, magnetic stripe reader, bluetooth, RFID reader cards with an extra gig of expanded memory.
If you add expansion hardware, you have more worries because of the extra power consumption. Even with no added hardware, a good run for a Pocket PC is about four hours of continuous use or a full workday of intermittent use. Some PDAs have replaceable batteries, but most do not. So when the power is gone, the user has no choice but to plug it in for a recharge. Even worse, some PDAs don't have a backup battery, so when they lose all power, they also lose all the data and programs that have been installed since being taken out of the box. Don't forget that a Pocket PC is always using power, even when it is turned off.
Another concern is the PDA's capacity to have an always-on network connection. Some PDAs do have built-in WiFi; if not, it can probably be added using an expansion card. But these WiFi radios really drain the power out of a battery. For purely experimental reasons, I once tried to continually browse the Web during a staff meeting, but my PDA died before the two-hour meeting ended. Even without worrying about the power use from a WiFi radio, an always-on network connection still cannot be counted on. Establishing a network connection can take up to a minute or two (even worse if you have to use VPN software). For a device that can turn on in less than a second, making this initial network connection will seem like an eternity to the user.