Six years later, Windows 7 is in the rear-view mirror. I wrote it in late 2009, and posted a follow-up one year later If you had followed my advice, you could have saved hundreds of dollars on upgrades and special deals for students and IT pros.
Updated November 25, 2015: One of the most popular posts I have ever published at ZDNet was this one, originally titled Seven perfectly legal ways to get Windows 7 cheap (or even free).