Well, a little searching found a Windows version of the turbo.264 hardware. It's call ADS InstantVideo To-Go. Prices seem to run from $60-$70. Have no idea how good the product is, since I don't do WIndows.

I've used my version to copy HDTV shows I've recorded and edited the commercials out of to watch them on my iPod when I have nothing else to do. and to convert some old videos and home movies to the iPod. For me the coprocessor make a significant improvement in conversion times, and I've got 2.33ghz Macbook Pro. I haven't measured it, but it seems to cut conversion time in half, and also frees up the CPU in the computer to do other things while it's running, without impacting the conversion process.

The iPod only plays h264 and mp4 video files.