Errata

You tell the "onChange"-event for text input elements is triggered whenever the content changes. This is not correct, as while typing in a sequence of 10 letters, the onChange-event is NOT triggered 10 times as the reader would think.
In fact "onChange" should better be thought of as "onBlurAndChange", since the changyness is checked "on blur".

The css for the coffeeorder and coffeemaker2 divs does not render accurately in IE7
-- particularly, the coffeemaker2 block appears outside of and far right of the
wrapper division.

I found that changing the entries to match the following gave good results in both IE
and Firefox:

div#coffeeorder {
position: relative;
top: 20px; /* was 60px */
/* removed entry for left */
width: 100%; /* was 300px */
margin: 0;
/* removed entry for padding */
}

div#coffeemaker2 {
position: absolute;
top: 10px;
right:10px; /* was margin-left:520px; */
padding: 10px;
width: 200px;
background-color: #f5f5f5;
border:double medium black;
float: right;
}

I was unable to get the second coffee maker image to appear next to the coffee mug as it is listed in the pictures. I ended up moving the <div> from below the "controls1" <div> to above it and moving the <p id="clear"></p> line below the second coffee maker image.

I also added a <br /> to the <p id="clear></p> line to push the text down.

.
.
.
<div id="wrapper">
<div id="coffeemaker1">
<h2>Coffee Maker #1</h2>
<p><img src="images/coffee/CoffeeMaker1.gif" alt="Coffee Maker #1" /></p>
<div id="coffeemaker1-status">Idle</div>
</div>
<div id="coffeeorder">
<p><img src="images/coffee/coffeeMugWithBeans.jpg" alt="Coffee Pot 1" /></p>
</div>
<div id="coffeemaker2">
<h2>Coffee Maker #2</h2>
<p><img src="images/coffee/CoffeeMaker2.gif" alt="Coffee Maker #2" /></p>
<div id="coffeemaker2-status">Idle</div>
</div>
<p id="clear"><br /></p>
<h2>Place your coffee order here:</h2>
<div id="controls1">
.
.
.

This solved the problem for me in Firefox on both Linux and Windows. But then, I don't know if it was just and issue *I* was having or if it was a problem for anyone else.

var request = false;

should be

var request = null;

When visiting the web site
http://www.headfirstlabs.com/books/hrajax/chapter03/coffee/coffee.html

The coffee maker #2 image does not display on the page in IE 7,
but rather shows on the far right if you scroll over. It does display correctly in Firefox.

The question "Isn't there an addEventHandler() method?"

This should be addEventListener(), but it's still not supported in IE (and microsoft
have blogged that it won't be in IE7 either :( - maybe IE8).

In breakneck.css, the body declaration contains a font-size attribute that FireFox 3.0.7 is tossing.
font-size: 14; should be font-size: 14px;

"if ((message.length == null) || ..." should be
"if ((message == null) || ..."

The 3 vars to retrieve the values from the form should end in ".value" e.g var phone = document.getElementById("phone"); should be
var phone = document.getElementById("phone").value;

Using Firefox 3.0.8 and IE7

The PHP vars were not getting substituted upon return. I had to add the "php" to the opening <? to make it work.

Instead of ...

<totals>
<boards-sold><? echo $boardsSold; ?></boards-sold>
<boots-sold><? echo $bootsSold; ?></boots-sold>
<bindings-sold><? echo $bindingsSold; ?></bindings-sold>
</totals>

I had to code ...

<totals>
<boards-sold><?php echo $boardsSold; ?></boards-sold>
<boots-sold><?php echo $bootsSold; ?></boots-sold>
<bindings-sold><?php echo $bindingsSold; ?></bindings-sold>
</totals>

$bootsSold = 1672;
$boardsSold = 312;
$bindingsSold = 82;

should be

$boardsSold = 1672;
$bootsSold = 312;
$bindingsSold = 82;

this makes the example work correctly

php file getUpdatedSales.php initial values for boards and boots are reversed:

is:
// Start with an arbitrary number of sales
$bootsSold = 1672;
$boardsSold = 312;
$bindingsSold = 82;

s/b:
// Start with an arbitrary number of sales
$bootsSold = 312;
$boardsSold = 1672;
$bindingsSold = 82;

You may want to change the rand values to make the sales a little more dramatic:

is:
// Reflect new sales
srand((double)microtime() * 1000000);
$bootsSold = $bootsSold + rand(0,10);
$boardsSold = $boardsSold + rand(0,5);
$bindingsSold = $bindingsSold + rand(0,3);

s/b:
// Reflect new sales
srand((double)microtime() * 1000000);
$bootsSold = $bootsSold + rand(0,100);
$boardsSold = $boardsSold + rand(0,1000);
$bindingsSold = $bindingsSold + rand(0,100);