Lightroom vs. Photoshop & Bridge

Do I need Lightroom if I already have Photoshop or Gimp? Why not organize my pictures in Windows Explorer or Adobe Bridge and then do my detailed editing in Photoshop or Gimp? These are very reasonable question, and common ones too. For an answer, let you tell you my story. A story that begins even before I bought my first DSLR and by the end, you'll know why I use and recommend the system I currently have.