This is the USB-MIDI Cable
that I use with my CDP-100. Apparently there are some people that have had problems with the cable, but mine has been solid so far (1-2 months of almost daily use). I figured it was worth the $5 to try it out before I bought a $30 from Guitar Center, but it was sort of a gamble. It's not the fastest/best cable out there, but works without any problems for me.
Just for reference here are my setup specs:
MIDI to USB cable mentioned already
Dell Vostro - Windows 7, 64-bit
I use the default driver that installed itself when I plugged the cable in, then installed ASIO4ALL drivers to run Pianoteq through VSTHost. After changing some of the sample settings it works now with no latency issues.