They never really "lost" me either. I stayed faithful to them through the N64 era (I'm one of those people who was not really impressed with the PS1, save for a handful of titles). My monogamy to them did, however, end during the Gamecube era. It did take a little while (and the release of Mario Galaxy) to finally get me onboard with the Wii, but the fact that it is 100% backwards compatible with the GC titles did make my purchasing decision alot easier. I am disappointed, however, that Nintendo chose to pursue motion control gimmickry over more powerful hardware for this generation. If they had delivered the Wii with the muscle needed to directly compete with the PS3 or 360 library of HD games, this generation of console wars would have been a massacre.
As long as great new Mario, Metroid, Smash Brothers, Mario Kart, and Zelda titles continue to appear...I have no intentions of abandoning Nintendo.