Windows XP User Icons…
You can customize the icon that appears on your Windows Welcome screen and on your start menu.
To change your Windows XP user icon, click on your Start menu, then click the icon beside your name.
A new window will pop up prompting you to “Pick a new picture for your account”. Several icons should appear, giving you the option to change your picture.
Add an icon of your own design by clicking “Browse for more pictures”. You can choose any existing picture of any size because Windows will shrink and expand the picture to fit perfectly. However, it will look a lot better if you create your own 48×48-pixel icon in Photoshop or a similar image-editing tool first.
If you’re looking for user account icons and chat icons, give this site a shot. Updated surprisingly frequently.