Originally Posted by Five

you need a soundcard with a coax or optical in (whichever your DAT deck has). Then you get the special cable, run it from the DAT to your laptop's digital in. Be sure you capture it at the same bitdepth and frequency that each original DAT is recorded at. I'm pretty sure the bit depth is 16bit, the frequency will (hopefully) be 44.1kHz, but might be 48kHz. Check the led display on the DAT deck for this info. Do you have a prog to record onto your laptop with? Audacity can do it and is free, but a few changes in the settings will be necessary to make sure that you get the best direct digital copy possible.

congrats on unearthing this goldmine!