Most of us all have a good anti-virus program and are suspicious of getting e-mails with funny attachments, be those .exe, .pif, .bat, .scr, or other types of script or executable files. We tend not to open those, because we are suspicious about viruses, and while opening the e-mail file containing these attachments is not harmful in itself, double-clicking on those attachments can infect our computers with some really malicious viruses.

Well, that is no longer true anymore. Nowadays, even visiting a web site that contains some malicious JPEG pictures can be harmful. Microsoft warned last week that users who had not yet downloaded the Super Pack 2 upgrade to Windows XP are vulnerable to a flaw in the way the Windows OS handles the common JPEG file format. Dubbed "buffer overrun", this can be a way for some hackers to get bad code such as viruses or worms onto target machines.

Bottom line is all it takes for a user's PC to become infected is to visit a site with Internet Explorer that contains these specially crafted "bad" JPEGs. Other programs at risk include Office XP 2003, Office 2003, Internet Explorer 6 and other versions of Digital Image Pro and Picture It.

However, the good news is that users who have already downloaded Microsoft's Windows XP SP2 (Service Pack 2) will not be affected. My recommendation: if you haven't done so, the time has come for you to download and install SP2.