Ed Bott posted an analysis of “how Microsoft releases service packs and other major Windows updates,” after reading several reports suggesting that Microsoft was “rushing” Service Pack 2 for Windows Vista.

They all need to dust off their Windows history books to see that the reality is exactly the opposite. If Vista SP2 does make its official appearance in April, it will mark a return to normal development and release cycles for Microsoft, which lost its way badly with Windows XP.

I’ve got the proof, in easy-to-read chart format. Here’s a timeline of every Windows service pack Microsoft has delivered since the release of Windows NT 4.0 in July 1996. Each color-coded bar represents the number of days between each service pack and its predecessor (RTM, in the case of SP1 releases). See any patterns?