I use USB for both. I have a Microsoft Internet Keyboard Pro and a Microsoft Trackball Optical. My keyboard is connected to a USB port on my PC and my Trackball is connected to the hub of my keyboard. Actually, you can save an IRQ if you connect them all to USB and disable your PS/2 ports. Also, mice are more responsive when connected to USB.
AMD technology + Intel technology = Intel/AMD Pentathlon IV; the <b>ULTIMATE</b> PC processor