I get this question alot, and it's really such an individual answer. I found this article online that may help you decide. Still need help? Give us a shout and we'll be happy to answer any of your questions and even get you started on one or both of the programs!
Photoshop or Lightroom?
Photoshop’s strengths
Pixel-level editing
Layers
Actions
Compositing and blending
Huge toolbox
much more
Lightroom’s strengths
Built-in RAW editing
Image management and workflow centric
Simple and easy to use
Presets
much more