there are no adapters that convert ps2 ports to usb. by port, i refer to the end at your motherboard.
there are adapters that convert ps2 plugs to usb plugs. by plug, i refer to the end at your mouse\keyboard.
the serial port to ps2 don't exist. there are ones that convert plugs, however, unless your mouse was designed to accept serial AND ps2, they are useless. converting a serial port to usb is retarded.