I have heard of pre-programmed SD cards not working, though this may have been due to last fall's transition from 256MB to 512MB. You might get some useful suggestions in this thread: New Raspberry Pi w/ 512mb - DOA?
Ive tried 3 PSU (Pwer Supply USB ) Plug in devices an though they say they are 1000Ma im still getting mo power
on my PI , so where can i get a guarenteed 100% out of the box power supply and Cable that works with the PI
Im using Ethernet , HDMI, USB Keyb Mouse / SD card , all required and that must be taken into consideration for
power requirmetns on startup ...