The best way to avoid catching the virus is to ensure that your anti-virus
software is up to date and to ensure you don't open e-mail attachments.
There is no 'patch' for this worm - it relies on people who have not
protected their machines properly or who engage in unsafe e-mail practices.
You may be able to upgrade your e-mail client to provide additional
protection against opening unsafe attachments. See:
http://www.microsoft.com/security/incident/mass_mailer.asp