Part of your OS is trying to connect to the internet to carryout an 'Automatic Update'. Look at programmes such as ZoneAlarm, your antivirus and adware programmes. Windows is also set to look for updates automatically, by default.
Use the control panel 'Adminastrative Tools'.. click on 'Component Services'..'Services Local'.. and look for 'Automatic Updates' switch this to manual.. also switch the following service to manual:-
Remote Access Auto Connection Manager
Check that your not allowing the windows clock to automatically update itself (double click the clock in the taskbar and click the Internet Time tab.. and uncheck the 'Automatically Sycronise the time with the net server'