There was some issue relating to a particular flavour of USB host chipset (AMD, I think) which was only fixed in one of the version 7 releases.
I would think you need to make sure that you are using the latest empeg player version ('cos that's where the driver lives). I found that if I powered off, connected the supplied cable (A-B type) then powered the empeg on first, then W98 second, you should be rewarded with the "recognised new hardware" message as 98 starts, which should pull up the driver. You can check it has found it from the control panel/system/USB device list to see if it's there.
At this point, you can start emplode - by default it looks for USB first, then serial. If you don't get a connect, then the recommended action was to flash the developer version, connect a serial line (115k 8N1 NO handshaking) and capture the screen output as you re-start empeg and attempt a USB connect. ZIP the result and post it to bugs@empeg.com.
I wish you had posted this in the correct forum, too