Well it has been release Microsoft issued an update to the system:

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Vulnerabilities in SMB Could Allow Remote Code Execution

Microsoft Security Bulletin MS09-001 – Critical (KB958687)

This security update resolves several privately reported vulnerabilities in Microsoft Server Message Block (SMB) Protocol. The vulnerabilities could allow remote code execution on affected systems. An attacker who successfully exploited these vulnerabilities could install programs; view, change, or delete data; or create new accounts with full user rights. Firewall best practices and standard default firewall configurations can help protect networks from attacks that originate outside the enterprise perimeter. Best practices recommend that systems that are connected to the Internet have a minimal number of ports exposed.

This is one of those updates you really need to install as soon as you can.   You should also get a free firewall or buy one.  I looks to be a vulnerability in the ports and if you’d have a firewall besides windows you should be safe but that is besides the point.   If you are security congenious then you should install this update ASAP.  If your worried this will effect you system then you will need to backup your system before you do this update.  If you feel you’ve might of been infected with this Vulnerability you could always go get a free antivirus program and scan your system.  This is the sure way of fighting a Virus and making sure your safe, although people argue that Paid virus programs are quicker to be updated with virus databases, it’s all in the matter of preferences.