No, a 3x8 pin grid is not a 25-pin serial port. In fact, only the oldest of computers would even have a 25 pin serial port. Your Dell definitely does not have one.

If Hyperterminal can't see the player, then there's something wrong with the serial connection at the low level. Either it's a problem with the USB-to-serial adapter, you're picking the wrong serial port number, or (more likely) you've got the wrong kind of serial cable connecting your PC to the empeg, or the serial cable is faulty. Remember that the serial cable must be a null-modem cable (with the RX and TX wires crossed).

There have been reports that some USB-to-serial adapters don't work for player upgrades or kernel flashes. But even if that were the case with yours, you would at LEAST see text in hyperterminal when you cycle the power on the player.

The fact that you're not seeing anything in hyperterminal means there's something else wrong. You need to get the serial port and serial cable working.

Or... Just give up and find a friend with a serial port.