Sorry If I over egg the pudding but not entirely sure about how to answer.
Usually you need a 5.1 processor found in Home Cinema AMPs and the like. You can only achieve 5.1 surround sound with 6 speakers. Two at the rear, two at either side - a centre speaker for sound and a sub woofer. Your TV may be capable of producing this sound (i'd double check in the instructions) but if you dont have the speakers you will only hear Dolby Digital from your TV's speakers. Your DVD recorder will be able to play 5.1 surround sound (presuming it's not very old)which is usually a seperate audio chanel on a DVD disk but the full benefits are only heard if you have the 6 speakers. It will come through your TV, normally as Dolby Stereo and you should choose that option when watching a DVD - it's usually audio option 1, 2 being the 5.1 surround sound option.
Your DVD player will more than likely play dolby stereo - the difference between this and NICAM are minimal
You will need all the correct connectors too.
I hope this makes sense ??