Interface Cards & Controllers

I just upgraded my pc today. Got a hd 6970 and a new hdd which is the WD 750gb 64mb cache 6gb/s.
My motherboard doesn't support sata 6gb/s so i got a ASUS pci card which has usb3.0 and sata 6gb/s. Here is the link to them both:

http://www.scan.co.uk/products/750gb-western-digital-wd7502aaex-7200rpm-64mb-sata-6gb-s-35

http://www.scan.co.uk/products/asus-u3s6-true-2-port-sata3-%286gbps%29-and-2-port-usb30-superspeed-pci-e-combo-controller-with-ncq

Ive installed the drivers and have the HDD plugged into the PCI card. But i haven't really seen much speed difference and im not sure if its actually running is 6gb/s. I downloaded HDTach which is a HDD tester and it shows that my Burst speed is around 3gb which makes me think its still running in 3gb/s. IS there anything im doing wrong? do i have to use jumpers on certain pins on the HDD to enable 6gb/s or is there a option in the PCI drivers or something? Please help!!

Thanks.