4.1 sound vs. 5.1 sound- what's the difference?

[bupkus]

I'm using 4.1 sound from my IWILL KK266 mainboard. I purchased the Boston Acoustic 4800 speaker system to be delivered this tuesday.
When I use PowerDVD I have some choices between 5.1 sound and stero. I don't know what is used with computer games but I have what I have and I'm wondering which setting I should use. I don't see many 4.1 settings so maybe I should just use the 5.1 and ignore the fact that I only have 4.1. What's the deal here?

 

[Pariah]

5.1 is for movie surround sound settings. The additional channel over 4.1, is a center channel which the majority of speech is directed in movies. Use 4.1 if you have only 4 speakers.

 

[yellowperil]

Under 4.1 the two front satellites 'matrix' the sound to form an invisible center speaker (this is using Dolby Pro Logic decoding). With 5.1 the center channel is discrete (in Dolby Digital 5.1/DTS decoding). The center channel is used mainly for dialogue in movies. I think that's the main difference. Like Pariah said, use 4.1.