Connect it for what? You can certainly connect the Motif to the sound card's audio inputs for recording. All you need for that is 1 or more 1/4" cables.
You can connect it via MIDI to your sound card's MIDI inputs. I am not familiar with your card but I just looked at a picture. It looks like you would need one of those little breakout cables that plug into the 15-pin jack there on the card.
You can also plug a USB cable from the Motif to the PC, which will act as a MIDI connection. If you do it this way, you don't need MIDI cables.
This will enable you to record MIDI or audio into your PC. If you are talking about connecting it for file transfer (like getting samples from the PC to the MO or vice versa,) then that's a different story. You can transfer voice information over USB, but that's about it. For trading files between the two, you really need a Smart Media card and a card reader. This is the easiest, fastest way, and will only cost about $20-$30 for the reader.
Let me know if this is what you mean and I can try to clarify if necessary.
Also, a really good resource for info on the Motif is
www.motifator.com. They have lots of info and a good forum as well.