So I put a 2 GB card in my phone. The phone recognized the card ok, I was able to take pictures and save to the card, and able to do file transfers from my PC with Bluetooth, but the PC did not see my memory card when using the USB cable.
So, I did a phone software update. I think I updated from ZH11 to ZK03, and when I checked for an update, the notes specifically said this update would add support for a 2 GB microSD card.
The update date only took a couple of minutes, and now my PC sees the memory card via USB cable just fine.