On palm units, screens are roughly 4 inches across the diagonal with resolutions up to 240x320. Typical handhelds have larger screens around 6.5 inches diagonally, supporting 640x240 resolution. If you want a handheld with even better image quality, Pro models can support resolutions of 640x480 and 800x600 with screens around 10 inches in size. Memory PDAs employ memory to store the operating system, standard applications and additional programs. Memory is also used for working space and data storage.
More memory is usually better because it increases processing speed.
However, it's difficult to compare storage capacity between models with different operating systems. One model with 4 MB of RAM could store more data than another 4 MB model with a different operating system. Most devices already have sufficient memory to store all the personal information of a typical user. If you want to load up on applications, look for a PDA that has upgradeable memory or supports removable storage like CompactFlash or PC Cards. The down side of adding memory is increased battery drain.