Well the "speaker cable", unplug it and use "standard audio cable" to interconnect the audio out to the audio in on your mobo.

Pardon the hurried illustrations, but you get the point dont you>?.
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ALTERNATIVELY
If you want absolutely the best, get
ADOBE PREMIERE. It has got everything youll ever need. But unfortunately you will have to pay
....or um... "use" the internet
Cheers.