More and more notebooks and even desktops don’t come with older PS/2 adapters. If you’re not quite ready to give up your older mouse and keyboard (like me with my original Microsoft ergonomic keyboard), then the Brando USB to PS/2 Adapter is what you are looking for. It supports up to two PS/2 devices at the same time and is compliant with the USB HID specification. All in a package that weighs only 15 grams.
The Brando USB to PS/2 Adapter is available for $7.00 USD.
Source: Mobility Site