Watch hdtv on my laptop with 5.1 sound?

So i just built a new system, and i have an hd cable box that i want to watch on my monitor. The problem is that i'm not sure how to watch it so that i use my monitor and my good speakers (my monitor speakers suck)

my cable box has an hdmi out

my monitor has hdmi in and spdif out (its an asus vh236)

my computer has an asus p6t motherboard and no sound card (i use the mobo). the sound ports on the mobo are optical and coaxial spdif out, and then rear speakers out, front speakers out, center and sub out, line in, and side speakers out

my speakers are logitech x-540, so they have no spdif in or anything.

i want to get alll 6 channels of sound when i watch hdtv, but i don't want to get a tv tuner.

any ideas? would the spdif out on the mobo take spdif in?

OK for what I can see you might get audio and video but no 5.1 audio without buying more hardware. if you connect the HDMI to the monitor and RCA from the cable box to the back of the speakers you will get video and audio. Unless you find in the control panel/ audio a way to change s/pdif to input (I doubt it) there is no way for you to use your computer without buying more hardware. most likely a sound card http://www.newegg.com/Product/Prod [...] 6829111001 I don't know if this one is good but as you can see it has an coaxial input then you could connect the HDMI to the monitor then a coaxial cable from the monitor to the computer and out to your speakers,

also you might have an coaxial output on you cable box then you might be able to get the audio straight from the cable box to the computer then to the speakers.

NOTE: Make sure to adjust the settings on the cable box to whatever connections you choose. Weather is RCA, Coaxial or HDMI. Please let me know of the outcome.