If you use Google Talk, you can create chat and talk shortcuts for specific contacts directly on your Windows XP desktop. All you need to know is the email address of your contact.

To create the shortcut, right click on the Desktop and select New -> Shortcut.

For the location enter the following a chat shortcut:

gtalk:chat?jid=EMAIL

and for a talk shortcut enter

gtalk:talk?jid=EMAIL

In both cases, you need to replace EMAIL with the actual email address of your contact.

Once you enter the location, click the Next button. You'll then have the opportunity to name your shortcut.

Once the shortcut is created, you can then start a talk or chat session with your contact by just double clicking on the desktop shortcut.