Hi Jeff,
Welcome to Laptop GPS World forums!
I have personally never owned a Garmin Etrex, but I've heard of people successfully using it as a GPS receiver for a laptop PC. If memory serves me well, it I believe involves using either a serial cable connection (but most laptops these days no longer have serial ports), or using a USB adapter of some kind. It could even work with a USB cable and Franson GPS Gate software.
However, if you have to buy anything for your Etrex to accommodate this function, you may be better off just buying a simple USB GPS receiver. They can be purchased for about $50 or even less these days. That's much less than they used to be few short years ago.