Keyboard Help

I recentely purchased a PS/2 to USB adapter from amazon.com. I have an old keyboard that I wanted to plug into my laptop for multiple reasons. I connected the adapter to the keyboard, and then plugged it into my computer. It did not seem to be working, so I went to my system profiler and under USB, the keyboard did not show up. Is there any drivers or any way I can get the keyboard to work on my Mac iBook?? Thank you for the help.