Amazon seems to have a slight mistake on their Creative X-Fi Promo so that the two discounts stack:
Creative Sound Blaster X-fi Platinum ( 70SB0460000001 ) $174.99 - $50 Rebate - $25 Promo -$15 Additional promo = $84,99!!
Creative Sound Blaster X-fi Platinum ( 70SB0460000001 ) $174.99 - $50 Rebate - $25 Promo -$15 Additional promo = $84,99!!