Hi I'm on the lookout for a home cinema system but I know little about them!

I want to be able to have it so that anything I'm watching on the TV comes through the cinema system - at the moment I've got a V+ box and a DVD player connected individually via HDMI to my TV - can I connect a DVD player and V+ box to a home cinema system so both will come through it? If so, any recommendations from anyone please? And do I have to buy a new DVD player because I notice that all the systems seem to come with a DVD player? Thanks for any help.