Microsoft is claiming that the newer generation of 64-bit computers running Windows is safer than 32-bit versions.
The blog entry states that there is less "malware" -- bad stuff like viruses and worms -- out there attacking 64-bit computers. 64-bit is found mostly on newer hardware (a more detailed discussion of the differences between the two types can be found here.)
If you bought a new computer with Windows 7 on it, chances are good that it's a 64-bit machine. If that's the case, you should be more safe than those running previous Windows versions, including XP and Vista. Here's how the blog writer summed it up:
"Overall, 64-bit malware is still exceedingly rare in the wild, and the additional protections built into 64-bit Windows will make it harder for malware to make the 64-bit jump that's easy for PC users with Windows 7."
That does not mean your computer is invulnerable; just that it's less likely, at least at present, to be attacked. Learn how to protect your PC on About.com's antivirus site.