New PCs received over holidays should be updated right away
While Windows 7 and Office 2010 are much more secure than prior operating systems, it's still essential to ensure a new PC is updated for all Microsoft security patches, as well as all other vendor software, (e.g., Adobe Flash). This should be done immediately, along with setting up complex passwords, limited accounts, and other safety measures.
December 2010 - Very Large Security release
http://isc.sans.edu/diary.html?storyid=10081
Windows Update Site
(Choose the new Microsoft update to also include Office and other Microsoft products)
http://windowsupdate.microsoft.com/