If your textbox has the AcceptReturn property set to false (the default),  
and you have a button on the form set to be the default action button for  
the form, then you can just hook an event handler to that button.  In the  
event handler, just get the Text property from your textbox control.

If you don't have a button set as the default action, then you can still  
do it, but you instead need to handle the KeyDown or KeyPress event for  
the form (if you want it to always happen) or the control (if you want it  
to happen only when that control has focus), and get the Text property  
when you get the event with the Enter button as the key that was pushed.

Pete