It would help if you gave the model number of this Creative Labs SB.
Some of the newer 5.1 speakers come with a switch for 4.1, 5.1, 6.1.
Like my Labtecs X-620 6.1 (and 5.1 or 4.1 setting).
Got them as refurbished off w.Ebay.com from Justdeals.com
$33 (including shipping), speakers were in "like new" condition.
For a cheap 5.1 sound card replacement, my Turtle Beach Santa Cruz
was used off Ebay.ocm for $20.50, Does 5.1 speaker
and has quality hardware (card was $100 when they first came out)
Or the Chaintech AV-710 usualying $25
The card uses a VIA Envy HT-S chip
Should have good driver update support.