It's the second Tuesday of the month, so that means it must be Patch Tuesday! Microsoft has released four updates that most Windows XP computers will need, three of which are rated critical. One of the patches fixes a problem that has had exploit code posted publicly since December, so I recommend patching systems as soon as possible. (It seems like I make that same recommendation every month, probably because almost every month there is at least one patch that fixes something "scary.")
For more information about patching and keeping your computers up to date, see my first Patch Tuesday blog entry.