Most IT professionals are already aware that Microsoft routinely publishes updates to their operating systems on the second Tuesday of each month, early notification and download access is also available to select groups.
There are also several semi-automated tools that will scan your Windows computer on demand to list updates that are available to you.
I should mention that while the application from Secunia only scans Windows, their website discusses updates for most other popular operating systems and software
Have a happy and safe 2008!