You can see the differences between Mainstream and Extended Support (as defined by Microsoft) here: http://support.microsoft.com/gp/lifepolicy
The only Microsoft Support features most people use are Security update support
, Product-specific information that is available by using the online Microsoft Knowledge Base
, and Product-specific information that is available by using the Support site at Microsoft Help and Support
, all of which are also part of Extended Support. For most people the only difference between Mainstream and Extended Support would be No-charge incident support
and Warranty claims
. Note that neither of those support features are included with OEM versions, which are what most people get with their systems. In other words for most people using systems sold with Windows included there is no difference between Mainstream and Extended Support. Scott.