That's as secure as a bottle of Talisker within 100 miles of Spinola
SOFTWARE giant Microsoft might have been a tad hasty when it thought that old file formats should be killed off by the latest service pack for Office 2003 SP3.
A security advisory in December warned of great plagues of fruitbats, slugs and tax collectors if users used dozens of old file formats. However, the Vole was going to save them from all their security problems by blocking the formats.
Unfortunately users were furious and wanted to still use them.
The helpful Vole provided a workaround for users who want to unblock the formats but the process was so complicated that it made the refinement of uranium look like something an Iranian boffin could do over his tea break.
Now it looks like the helpful Voles have finally fessed up that they were wrong. First they realised that the problem actually affected more than one person with Windows 95 and his dog, Colin. Next they worked out that it was not the file formats that were insecure it was the parsing code that Office 2003 uses to open and save the file types.
Microsoft has updated the advisory and included links to four downloadable updates to unblock the file formats.
Writing in his bog David LeBlanc , a senior software development engineer in the Microsoft Office group said it was an easy mistake to make.
The Vole noticed that attackers seemed to be preferentially hitting the parsers for the older formats.
If the world plus dog didn't need the older formats, it was easer to kill them off, the unhinged logic ran. ยต
"The helpful Vole provided a workaround for users who want to unblock the formats but the process was so complicated that it made the refinement of uranium look like something an Iranian boffin could do over his tea break."

Hahahahaha! I love you Brits... your humour is most amusing.
A reference to Spaced inside a file format article, hilarious
An easy mistake...is it really? because most security issues involve microsoft operating systems. Is it not easy to simply block them all?

Thank god microsoft do not actually make firewalls.
if isnt for those humors i've never been bothered to read inq everyday!! LOL

best one for this year currently should be "boring 787"
I don't know if you missed this or if you chose not to mention it but the real reason that MS did this maneuver was to get everyone off the old Office formats and onto the new ones. 

MS has used it's formats to block competition in the past and they are desperately trying to get everyone onto the newest formats before ODF (the Open Document Format) gains enough traction to hurt their business. This whole move was strategic: "Let's just switch off the old formats and see what happens". If it worked they would be very happy and if it didn't they wouldn't have lost anything.

Let's face it they couldn't care less about the users, this was an experiment to see if they could implement a major changover to the newer formats to exclude competitors. They lost nothing in the attempt except maybe got some bad PR, and let's face it MS has never been too concerned about their image now have they?
I agree completely with Martins comments but I think Microsoft have largely achieved the desired result of forcing users off the old office versions anyway.

How many users will be aware of, let alone able to apply these unblocking updates.

As a current user of office 97, I can now expect a growing number of other people I need to communicate with to be unable to open any office documents I send them.

Unless of course I stump up the money for office 2007.
You say that 
<blockquote>Writing in his <i>bog</i> David LeBlanc, a senior software development engineer in the Microsoft Office group said it was an easy mistake to make.</blockquote>
You know "bog" is a UK English euphemism for "toilet". Quite apt really!
There is one thing missing in all these discussions of Microsoft and their planned, designed-in obsolesce. If there were no market, there would be no product!!!!! Now I am anything but a M$ booster, but if individuals AND companies would speak with their dollars and say, "We are not always able to communicate with what we have and we don't want anything that will further complicate this process." This discussion would not exist.