Are you sure you have a signal convertor rather than an adapter?
http://www.clickykeyboards.com/index.cfm/fa/items.main/parentcat/11298/subcatid/0/id/124184 explains the difference.
Question: My cheap ps/2-USB green or purple adapter is not auto-detected by Windows plug and play and I can’t get it to work. Where can I download the drivers?
Answer: The vast majority of commonly available ps2 to USB converters are simple passive ADAPTERS that simply change the plug shape to match the outlet. These ADAPTERS only function to connect the ps/2 wires to the approximate USB wires. Simple ps/2 to USB adapters do not use specific software drivers.
In general, most users having trouble connecting their keyboard to newer computers are looking for a ps/2 to USB signal CONVERTER. These devices use an integrated circuit (pre-programmed chip) to actively translate the ps/2 keyboard signal and convert it into a USB keyboard signal.
This allows the vintage ps/2 keyboard to be automatically recognized by the operating system as if it were a standard, modern USB keyboard. A well-designed active ps/2 to USB converter will use the built-in operating system drivers for a USB keyboard (for example in Microsoft Windows XP, kbdclass.sys and kbdhid.sys).
1The obvious question, have you restarted your Laptop after doing this? – Joe Taylor – 2011-07-12T14:22:37.767
Yes U also restarted the laptop. – Shahin – 2011-07-12T14:28:01.327
Silly question, but are you sure the adapter even works? Try it on another machine. – Shinrai – 2011-07-12T14:28:27.443
I don't like an USB port as a KB-/ mouseport. Am I a dissident? – Aki – 2011-07-13T14:18:39.253
1Please don't post your question multiple times. If you need to add more information to your question, use the edit link under your original post. – nhinkle – 2011-07-13T15:07:56.720