Do i need an audio or av receiver if i want sound from both tv and blu ray player?

i'm thinking about getting an 3d hdtv, blu ray player, and a 5.1 speaker system. here are the items i'm looking at: VIZIO VBR133, Yamaha NS-SP1800BL, and VIZIO E3D420VX. do i need a audio or av reciever? i'm not ever going to add anything else to this (e.g. xbox, ps3, etc). if i need one can you advise me on a good cheap unit? thanks.