I looked for the manual on this MB and all I can find is in Chinese. It does say on the site the MB is jumperless although you say it is jumpered.
Re-check your BIOS settings and the manual. I have never heard of on-board sound not being able to be disabled. (Of course there many things I've never heard.

)
Based on your info this is what I would do:
1. Ensure the jumper issue versus able/disabled.
2. Remove the soundcard in device manager.
3. Shut down.
4. Remove the soundcard and re-boot without it.
5. Check device manager to ensure that you have no soundcards listed. (you should not have any if everything is going right)
6. If #5 has checked out shut down and re-install your card.
7. Re-boot.
8.
DO NOT LET WIN ME INSTALL THE NEW HARDWARE!!! Cancel any installation attempt of the card.
9. Re-check device manager to ensure there are no cards listed.
10. Pop in the CD from Creative and install from there. The menu should be obvious. If not there should be an install gudie on the CD.
(I'd tell you what to look for but have no idea where my 12 year old put my 5.1 CD

)
11. After install is complete check device manager to ensure that it is listed properly. Creative should be listed.
12. Just for the hell of it .... re-boot.

13. Re-check device manager .... just for the hell of it.

14. If OK, now try to install the software.
15. Good luck and post back your results.
Bill