Outlook XP is immune to the Klez virus. However, you may still receive copies of infected emails, which you may simply delete.

Here is what Microsoft has to say about prevention:

PREVENTION:

Install the patch that is associated with Microsoft Security Bulletin MS01-020. Because Microsoft Security Bulletin MS01-020 has been superceded, you must install the patch for Microsoft Security Bulletin MS01-027 (which includes the functionality of MS01-020). You can download the patch for MS01-027 at the following Microsoft Web site:

http://www.microsoft.com/technet/sec...n/ms01-027.asp

If you have already installed the patch, the following prevention details apply:

Outlook 2000 post SR1 and Outlook XP include the functionality to block harmful attachment types. If you are running either of these versions, they will (by default) block the attachment, and you will be unable to open it.


By default, Outlook 2000 pre SR1 and Outlook 98 do not include this functionality, but it can be obtained by installing the Outlook E-mail Security Update. More information about the Outlook E-mail Security Update can be found here:

http://office.microsoft.com/Download.../Out2ksec.aspx


Outlook Express 6 can be configured to block access to potentially-damaging attachments. Information about how to configure this can be found here:

http://support.microsoft.com/default...;en-us;Q291387


Outlook Express all other versions: Previous versions of Outlook Express do not contain attachment-blocking functionality. Please exercise extreme caution when opening unsolicited e-mail messages with attachments.


Web-based e-mail programs: Use of a application-level firewall can protect you from being infected with this virus through Web-based e-mail programs.