The Windows XP update SP3 released 7/9/08 is incompatible with Zone Alarm firewall. You will not be able to get on the Internet after the patch is installed. It took me hours to figure out why I could not access the Internet today. If you're reading this you probably don't have this problem. If you have another computer or a friend who can not access the Internet here's a work around from PC MAG.
http://blogs.pcmag.com/securitywatch/2008/07/microsoft_dns_patch_grounds_zo_1.php
http://blogs.pcmag.com/securitywatch/2008/07/microsoft_dns_patch_grounds_zo_1.php