Here's the trick:
Search at Google for PL2303_Prolific_GPS_1013_20090319.zip looking (since it comes in a laptop GPS site ;-)) the simple download and install.
The driver version should now 3.3.2.105 (from 27.10.2008) be (to see Device Manager).
Newer drivers are not working. I now do not know what I would need the latest drivers, because the above-mentioned works just fine.
My Windows 7 64bit and Windows XP.
The adapter works fine under Mac (10.6.8) since just about the installation guide of prolific follow for MAC!
Star deduction for the stupid driver search!