Need help with new hard drive. I bought a new simpletech 320gb hi-speed usb 2.0 external hard

Question

I bought a new simpletech 320gb hi-speed usb 2.0 external hard drive and also a 2-port usb 2.0 pci card and installed them on my pc. After installing i went to systems and device manager and it showed they were installed and working properly but i am not able to transfer things from my local disk:c and also i am getting a symble in my task bar saying to safely remove hardware from my computer