I bought some landscape lights clearanced at Lowe’s a few months ago and have been waiting for the spring weather to install them. They are packaged 4 lights in a box and I bought 4 boxes. Each box comes with a power pack and the instructions are a joke. What I need to do is run one cable for the 16 lights. I cannot use 4 of the power packs so I will need to get a landscape transformer with a timer. I found a very helpful article that gives the formula to calculate the size transformer and how to lay everything out. Landscape Lighting Article
Updated 4/27/2010
I bought a 200 watt transformer that way I have enough power for expansion in the future. Along the back fence I installed nine 3 watt LED lights and two 15 watt LED spotlights and it just looks incredible at night. Also provides a little extra light for my mini schnauzer who likes to explore. If you do the math that would be 9 lights at 3 watts each which is 27 and 2 spotlights at 15 watts which is 30 so 57 watts total. I also went with a 16 guage cable to provide enough power to the lights.
So many projects and never enough time. It is amazing how much you can save and the value you bring to your home when you do these projects on your own.