USB-serial converter and com ports

I have been reading through the threads trying to figure out how to get my USB-serial converter (Prolific) to work in Parallels/Windows7. It is part of a USB GPS dongle. The device works perfectly in Mac OS X using navigation software written for MAC.
I start Parallels and Windows7, and look under devices->USB and see it listed as USB-Serial controller D with a checkmark. I open my windows based navigation program (seaclear) and it wants the com port. It seems to accept com 0 but there is no input from the device. COM1-10 don't work either.

I then installed the windows drivers for the device into Windows7 and tried the same thing. Again, I can't seem to tell seaclear where to look for the device. Mac doesn't seem to have anything like com ports.

I'm sure this subject has been beat into the ground, but I'm just too new at Mac (28 years with PC) to figure it out.

Thanks for your help,
Mike