From: http://www.ymouse.com/custom/ps2host.php



* Converts PS/2 input to Consumer Page HID USB data
* Accepts 2 keyboards, 2 mice (pointing devices), or one of each
* Works with our X–keys PS/2 Recorder software to copy X–keys programming

The P.I. Engineering PS/2 Host Emulator (DEV-211-XTPS2) allows the software developer to read raw data from a PS/2 keyboard or mouse (or pointing device), and offers two ports to accommodate two devices. Data from the devices appears on the USB HID Consumer Page in the Operating System. Data from the devices appears on the USB HID Consumer Page in the Operating System. Data from each device is tagged as either keyboard or mouse, coming from port 1 or port 2. P.I. Engineering offers a [free] Software Development Kit for Windows XP with examples and tools to help the programmer.

Not sure how this is better than a $5 monoprice.com USB to PS/2 except you can program PS/2 X-keys to kb codes that don't exist on regular kbs. Sort of. Maybe.