Ok, lets try one more thing. Plug the phone into the usb with your computer, and choose mass storage. Now double click on my computer in the start menu and it should show you any drives you have, do you see your phone or memory card listed?
If not then go back to the start menu, right click on my computer and choose properties, in the new box that pops up click the hardware tab, then device manager. In the list do you see anything with a yellow question mark or a red line through it?
If you do then right click that item and choose update driver and follow instructions on screen. If not then right click on the name of your computer at the top of the list and choose scan for hardware changes, that will make the computer to look for anything that's plugged in.