OK, here’s the deal.
I have a Nero installer, which came together with my old DVD writer. But when i upgraded my OS to Vista, my old Nero installer couldn't work any more and so I have to get a newer version of Nero, which in this case was Nero 7.
And luckily one of my buddy, flyjga, provided me with the serial number and it works fine. So if you would like to try out Nero 7, here’s the serial numbers you can try.