The SDC doesn't "push the button" to start the computer. it only "push the button" to shutdown. To start up, the mobo must support "Restore AC on power loss".
However you can search this forum or the12volt.com for "Constant to momentary" circuit.
In Windows Power Management, you have an option to either Shutdown or Hibernate when press the power button. That is what Mastero/Jefff SDC does, press the power button. Doesnt' matter what your option (Shutdown or Hibernate), the computer will turn off anyway. You need to turn on the computer again right? That SDC doesn't Press the power button to turn on the computer for you. Some mobo, there is an option in the BIOS "Restore on power loss" and set it to ON. The computer will automatically turn On when AC power is plug in to the PSU (or when the 5V STAND BY power is ready in the mobo).