Just got that message today:

[18:06:04] Scan Alert: WINDOWS REQUIRES IMMEDIATE ATTENTION
=============================

ATTENTION ! Security Center has detected
malware on your computer !

Affected Software:

Microsoft Windows Vista
Microsoft Windows XP
Microsoft Windows 2000
Microsoft Windows Server 2003

Impact of Vulnerability: Remote Code Execution / Virus Infection /
Unexpected shutdowns

Recommendation: Users running vulnerable version should install a repair
utility immediately

Your system IS affected, download the patch from the address below !
Failure to do so may result in severe computer malfunction.

http://www.scan-online.info/

For the link to become active, please click on 'Add to contacts' skype
button or type it in manually into your web browser !

I always think that it is very funny whenever someone tells me that my Windows box is affected since I'm running Linux.

On the other hand, I think it is really sad that some people do such things to others!