>Another option is to use touch screens, which are fairly inexpensive and in general give users faster 'point and click' operation than a mouse. No extra programming is necessary. Most of our fast paced retail customers are using touch screens. They love them.

We prefer touch screens too. But some of customers prefer the use classical desktop PC's or some of customers has old POS terminals which are don't support touch screen...

That's our POS main screen:

http://img504.imageshack.us/my.php?image=tposzi7.jpg