Running Windows XP? Microsoft says: DON'T
Microsoft is ending the support for XP which also includes automatic updates from Windows Update. This puts Windows XP in a highly vulnerable state after April 8, 2014 which is the date when the support ends.
Usually critical security issues within the Windows OS are found and fixed/updated every month, but with XP support ending this means that all security issues for XP that are found in the future will remain critical and unpatched!
Microsoft recommends getting a new PC or upgrading to Windows 8.1 (they don't mention Windows 7 but you could of course upgrade to Windows 7 as well). If you want to upgrade you should first verify that the hardware requirements for Windows 7/8 match your current PC as it may not work for older computers.
More information: http://windows.microsoft.com/en-US/windows/end-support-help
NOTE: This post in only about Windows XP itself, NOT about F-Secure products running on XP.
To my knowledge F-Secure will still support its products including updates for XP. For Business products F-Secure has informed about this in the End-point Security board, but for Home products I haven't seen anything which would indicate that XP will remain supported.