To allow ease of use for users that aren't accustomed to using the Tab key to switch between HTML elements and would prefer to use the Enter instead, simply add a OnKeyDown event handler to the element that changes a key code of 13 [Enter's value] to 9 [Tab's value].

For example:

<input type="text" onkeydown="if (event.keyCode==13) {event.keyCode=9; return event.keyCode }" id="text1">

<input type="text" id="text2">

After entering text into the text1 element, the user is allowed to press Enter [or Tab] to navigate to the text2 element.