I too am not a big fan of the new XP style Start menu, so I know exactly what you're talking about. Fortunately, it's pretty easy to switch once you know the secret...

Move your mouse over the Start button and right click your mouse (that is, click on the right button, not the left or center button), rather than the usual left click. Here's what you'll see:

As shown, choose Properties and you'll promptly be presented with the following window:

You can see I've selected "Classic" here: that's really all you need to do to switch menu styles and get back to the world you're used to from Win98.

However, if you're the sole user of your Windows system, there's one more thing well worth doing to make your sporadic administrative tasks easier. Click on "Customize..." adjacent to the Classic option shown, then you'll see a variety of changes you can apply to the classic start menu in WinXP:

Select Display Administrative Tools, then click "OK" to back out of this and change your menu and enjoyment of Windows XP!