Thanks for the responses. Hey Kornowski (long time no hear) - my problem is that every time I plug in my usb external HDD, the autorun function starts for each of the partitions and it's annoying to have to cancel it every time. BTW - I didn't know the "shift" trick with cds. thanks for that.
@SuzukiGSX1300R08:
I don't see an option to just disable autorun for that drive. Right-clicking gives me no option and the properties window doesn't have a single setting to completely disable autorun for that drive.
I went ahead an manually told it to "take no action" in each of the 4 cases that it offered options for (music, pics, vids, mixed). I did that for all 3 partitions. I guess that will work, but it would be nice to have a simple "check mark" that would turn it on and off.