This is a heads-up for all of you running Windows. There is a very bad virus going around right now called the "Windows Animated Cursor (ANI) Attack". It is one of the worst in years. An attacker can literally take control of your computer and do anything that you could do. Microsoft has just issued an emergency patch for this problem.
I STRONGLY ADVISE THAT YOU RUN WINDOWS UPDATE RIGHT NOW!!!
Here's more information from Microsoft regarding this issue:
Security Update for Windows XP (KB925902)
Date last published: 4/3/2007
Typical download size: 455 KB
A remote code execution vulnerability exists in the way that Windows handles cursor, animated cursor, and icon formats. An attacker could try to exploit the vulnerability by constructing a malicious cursor or icon file that could potentially allow remote code execution if a user visited a malicious Web site or viewed a specially crafted e-mail message. An attacker who successfully exploited this vulnerability could take complete control of an affected system.
Microsoft Security Advisory (935423)