The good news if you are runnning Windows XP professional.
The new vulnerability opens up the possibility for an attacker to send an email
with a malicious link. When the link is clicked by the email recipient on a PC
running Vista, it will execute a program on the personal computers
without warning.
The possibilities to inflict damage on your computers are endless, including but not limited to, loss of personal information, damage to your files stored on the local hard disk and so on.
Windows Mail is the successor to Outlook Express, Microsoft’s free e-mail client, and ships with Vista. The risk however is mitigated due to the fact that Vista is not widely accepted and used, yet, a fact that Microsoft has to accept with a pinch of salt.
Source: CNet News


