VDR needs a DVB tuner for receiving TV signal from satellite, cable or terrestrial transmitter. DVB-S card is for receiving digital signal from satellite, DVB-T is for receiving digital signal from terrestrial transmitter and DVB-C is for receiving digital signal from cable. VDR can use also analogue cards. It is also possible to receive signal with VDR server and stream it to the client.
There are many of kind tuner cards to choose from. There are PCI, PCI-e and USB cards available. V4L-DVB Wiki has good list of cards at http://www.linuxtv.org/wiki/index.php/Hardware_Device_Information