Dvd problems with surround sound

I got a new sound card and a new 5.1 surround sound system for my computer. i got the sound car hooked up but i didnt hook up any of the three cord in the top of the sound card. i hooked up the speakers they all work but the center speaker. i have it hooked up exactly like it shows on the box. i dont know why it wouldnt work the hook-ups are the same as it shows and the card i got is meant for 5.1 surround sound. This is the card i got

http://www.walmart.com/catalog/produ...248#long_descr

Everything else sounds great. Does any one know of any thing that i could do to fix the problem and get the speaker to work? This are the speakers i have

http://us.creative.com/products/prod...5&product=9303

Another problem is that when i put a dvd in my computer the sound will get all funny soundin but it wont do it at first it will sound perfectly fine and then go ape. when the sound skips so does the screen. ive used many different dvds and even brand new ones and they all make the same noise. everything else plays just fine even a cd in the same drive plays without a problem . i dont understand why it would do that. Can someone please help me? I would greatly appreciate any help u can give me.

do you have the drivers installed?

maybe your computer isnt 'good' enough to play DVDs (not enough RAM etc..)

Check Drivers (Download Latest, if not)

Unplug all speakers after you have done this.

Now using the wizard for your speakers, plug in 'Speaker 1' and test it out. If the sound appears when the PC is showing you, say, 'Top Left' then move your PC to that position. Do this one at a time to all of your speakers including your bass and you should be fine.

I got the dvds to work by just reformatting my computer with windows xp borg edition but i still cant get the center speaker to work.