First time building htpc

Hello I'm a noob building a htpc to go in my ht. The primary uses are going to be watching hd content at 1080p thru hdmi connection playing all my media and streaming movies from internet.I would also like to have 7.1 sound my receiver handles ddhd and dts- hd in bitstream or pcm. I am looking at using a silverstone crown cw02 as the case. Can't decide between Intel i3 or i5, if i5 is not needed will go with cheaper. If u guys have any suggestions it would be highly appreciated.would like to keep as affordable as possible but not afraid to spend xtra$$ for better performance. Thank u