Riddle me this:

What do you get after you install Microsoft's XP operating system and both of its humongous service packs?

Answer: Swiss cheese!

Apparently our friendly neighborhood virus creators showed how vulnerable XP is by taking advantage of three security holes in the much-maligned operating system over the Christmas holiday weekend.

Two of them targeted inefficiencies in computers operating with XP and SP1 and the third hit a vulnerability in SP2.

One of the vulnerabilities can be found in Loadimage, which loads icons, cursors and bitmaps onto your desktop. According to published reports, this can "open your system to exploitation." Loosely translated this can result in giving some malicious hacker access to your PC.

Another exploits a security hole in the Automatic Number Identification capabilities of XP. This little devil is activated when an unsuspecting user clicks on an e-mail containing an ANI file or clicks on a link that would load the file. The result could be a denial of service.

Both of these attacks are aimed at computers that have not been upgraded to SP2, so if you haven't taken the next step and downloaded and installed the new release from Microsoft, it may be a good idea to do so.

The third vulnerability, though, takes advantage of a hole in the Help system in SP1 and SP2.

All an unsuspecting user would have to do is run a help file and the system is "open to exploitation." The malicious attack is activated by opening an .hlp attachment sent in an e-mail or by reading e-mail in html format. The solution? Block all e-mails containing .hlp files and read messages in plain text format.

I cannot emphasize enough how important it is for XP users to keep up with updates and fixes that are posted on the Windows Update Web site and to install them when they are available. It is also essential that security software (virus protection, spyware sweepers, firewalls, etc.) be kept up-to-date by downloading updates to them whenever they become available.

And, most importantly, never open an attachment sent to you in an email from someone you don't know!

More information on these security holes can be found at www.symantec.com, www.Xfocus.org and at www.eWeek.com.