As other posters suggested, try to get a receiver only. You'll have many more inputs and outputs to play with than with a blueray/reciever combo.
The computer is a special case. You will either use HDMI , optical audio, or 6 separate analogue outputs from your computer...you'll likely have HDMI or optical. Most recievers accept these as inputs. As for software, you need to setup your operating system to use the appropriate output (HDMI, optical or analogue) for 5.1. You will likely be able to test each speaker separately from the software, which can be handy. It may be necessary to configure each media player you use (netflix, vlc, etc) to use the proper output as well.
Of course this all depends on your computer's components. If you don't have the appropriate outputs for 5.1, adding a piece of hardware might be necessary.