What is the best software??

I currently have Adobe Photoshop Elements 7 on my computer. I am trying to decide if it is worth getting a book to actually figure out how to use it to it's fullest, or if I should use something else. I have been playing around with a trial of Lightroom 3. Photoshop Cs5 is not in my budget right now. So if you had to choose between what I already have or Lightroom 3, what would the choice be??