Geekset.com has a nice video demonstration of the differences between a touchscreen and an active digitizer screen.
Its also worth noting that there are different types of touchscreen. A heavy-touch version which is good for writing with a stylus and avoiding errors (vectoring) caused by other parts of your hand touching the screen, or a light-touch version which is nice to use with fingers.
My personal favorite is the soft touchscreen as UMPCs are generally small enough that you don’t have to worry about other parts of your hand touching the screen. I’m also a believer that writing text with a stylus on UMPCs is not something most people in the mainstream markets would be interested in. Especially the markets where the lower-end and smaller devices are heading. For UMPCs, a soft touch screen will gain far more fans than ‘palm-rejection’ touchscreens.
Information on the types of screens that the various UMPCs have is in the product portal now. There are some devices that I don’t have the details for but most are covered now.
