According to ComputerWorld, “Microsoft releases patches to fix 20 flaws” in four Security Bulletins, MS04-011, -012, 013, and -014. All but one are rated critical. As the time between patch release and exploit seems to be dropping to a few days, I’d encourage you to patch your systems asap.
It’s the 16th week of the year. Microsoft’s patches and further information are available at http://www.microsoft.com/security.