If you require an SD card interface for your Arduino project I highly recommend purchasing an Arduino with one built-in.  It took three attempts to get an SD card interface added to my basic Arduino Mega:

1. A very cheap generic (“LC Studio”) break out module that seemed to work intermittently at best;
2. A cheap shield (linksprite SD Card Shield v1.0b) – not compatible with the Mega (it does not state this on the packaging but if you search the documentation on their website it clearly states this, I should have done my research first);
3. And finally, a not so cheap Ethernet plus SD card shield (Freetronics) that worked without a hitch.

I would have been better off spending the extra coin on a Mega with the SD card interface built-in and reclaiming most of my weekend…