Downloading a pirated version of Visual Studio 6 over a 56k modem definitely changed my life in high school, and allowed me to write code I wouldn't have otherwise been able to. (I still have those discs, mostly for nostalgia's sake.)

Of course what changed my life even more was subsequently downloading Slackware Linux (on that same 56k connection!) and realizing that I didn't need to pirate an expensive IDE to write code...