If your Vista has been kept updated regularly, you are already patched.
I got an alert from the Dell Support Center yesterday about the impending threat of the April Fools Day virus and was directed to a MS site where I was supposed to download a patch for this virus.  Once I downloaded it and tried to run it, I received a message that the patch was not compatible with my system.  I have an XPS 410 running Windows Vista Home Premium, SP1.  I can't understand why Dell put out this alert for my machine if it wasn't compatible.  Any comments/input will be appreciated.
MS Patch for April Fools Day Virus