Can you give me some advice about an adapter for a PC?

I have an old hand-held Garmin eTrex GPS and years ago I purchased a cord to download the info to my computer. One end of the cord has the fitting for the GPS, the other has a split tail with a cigarette lighter plug on one tail and an RS232 connector on the other. It worked fine with my old Win 7 machine.

I recently purchased a new desktop that has neither receptors. From what I read the best way to go is an adapter that goes from the RS232 to USB, in fact, Garmin offers one. Unfortunately it costs about half as much as a new GPS. Also, when I read the Garmin page it says it is not compatible in a 64 bit environment; something my new machine is/has.

It goes on to say “Requires applicable unit PC interface cable.” What does this mean? Does it mean I need my original cable to tie back into the GPS or what?

There are many adapters for purchase out there on the web for much less money. What do I need to know in order to purchase one that will work with my equipment and where can I find the information?