Well, if anyone is reading this, I figured out the Windows 7 64-bit thing.
The funny thing was it WASN'T a Windows problem at all. It took some time to eliminate possible issues.
Attempt 1) RDAS #1 connected to laptop using supplied new-in-package USB cable. The RDAS was not recognized, no messages good or bad, nothing. The altimeter is beeping the correct codes. After several attempts to get the PC to 'see' the altimeter on different USB ports...
Attempt 2) RDAS #2 connected to laptop using the same cable. Same result. Correct beep codes, but the device does not show up in device manager. Nada. The PC doesn't know it's connected. After trying all the same steps with the second altimeter...
It a chicken & egg thing. In Windows 7, you need to right click on a detected device to update the driver. If the device does not show up, there's no way to install the driver....
Attempt 3) Using RDAS #2, connect to the PC with a known working USB cable... YES!!! "Installing driver for device"
So, long story short, the supplied USB cable worked for power, but not for data. Both altimeters work with the good cable.
So much fun. I'm good now, happily playing with my new altimeters, looking forward to tossing them skyward, perhaps in something new at LDRS...