While most companies can effectively block this, it may be tough in cases where ZIP attachments are allowed and AV signature files haven't been published yet. The golden rule is to never open attachments.
Once the worm has infected a computer, it attempts to disable anti-virus and other security software. The worm also attempts to spread itself via file-sharing networks, posing as a number of different files, including a beta of Windows Longhorn, hardcore pornography, or a copy of Adobe Photoshop 9.