is certainly genuine, as is the Microsoft security bulletin mentioned on the page to which your link refers. The vulnerability is classed as 'critical' by Microsoft, and you need to do something about it.
You really don't need the Messenger service unless your computer is on a corporate network, and I suggest that you disable it. Here's how:
1. Click Start and then Control Panel
2. Click 'Administrative tools'
3. Double click 'Services'
4. Scroll down and highlight 'Messenger'
5. Right-click the highlighted line and choose Properties.
6. Click the STOP option.
7. Select Disable or Manual in the Startup Type scroll bar.
8. Click OK
Alternatively, and if you want to leave Messenger running, download the Microsoft patch from