Plug both drives in at the same time, open my computer (or computer if on vista) and you will see both drives listed as separate drive letters, double click on the old drive to open it so you can see the files and then press CTRL + A (this will select everything on the drive) then press CTRL + C (this will copy everything selected).
Then go back to my computer, open the new drive and Press CTRL + V (this will paste everything you have just copied onto the new drive)
It will probably take some time to copy everything across, just wait untill it's finished and job done.