How would i connect my pc to a 5.1 receiver?

[JSantiago]

My motherboard supports Dts connect and dts ultra pc 2 which means it has 7.1 or 5.1 surround sound support. 

1. What is better to use S/PDIF or analog output? or should i go with hdmi? 

2. For this combination to work do my receiver have special features that i should have for my computer to pass it through s/pdif/analog or hdmi? 

3. Is it the receiver's job to give power to the passive speakers?

[SantiagoManager]

Using an s/pdif would be your best bet for the most true sound. s/pdif is sometimes referred to as a TOSLINK cable. I recommend buying a couple because the cable inside is glass and if jerked like a regular cable then you can damage the cord. Your PC will need to have an output source of 5.1 to send 5.1 to a receiver. Often times bluray/DVDs will be authored with 5.1/7.1. 

I used to work tech support for a major player in home audio. It is basically all the same for the big ones YAMAHA, DENON etc... if you make sure your source is outputting the 5.1 and the correct drivers are installed then the receiver will process the signal and amplify it to your system. If you dont have a 5.1 feed and its a video game that is only broadcasting stereo then you will need to simulate the 5 channel audio from the receiver. 

I have included a link to buy spdif cables they are reasonably priced 
when you sign up for free trial of prime (second link) then you get free 2 day shipping on them too. Its pretty neat.