With Office 2007 on the shelves and shipping with machines worldwide, Microsoft is looking to stop the flow of the older Office 2003 suite onto new machines. About four years after release, they are now suspending licensing for it at the end of this month. While they will still be supporting the product for a long time to come, OEM versions will no longer be available once June 30th comes around, meaning PC retailers and other companies will need to switch to 2007 to include it on new machines.
Once existing supplies run dry, 2003 will disappear altogether from shelves and new PCs. As with most Microsoft products, companies or people wishing to use 2003 on a newer machine will be able to via the "downgrade rights" option on a retail license for Office 2007. As the article mentions, however, the same option is not available for OEM versions, which makes sense as OEM must be bundled with a machine.
Indeed, running Microsoft software is a privilege, not a right! That being said, ultimately it is always a good idea to keep systems up to date, particularly when Office exploits are so common. I wouldn't expect them to stop support for several years to come, and security updates for even longer, though.