Firstly, I don't think the second driver for the USB serial converter or whatever necessarily shows up for each PC, I think they're all unique in respect to that issue. At least it was for me, I had no issues getting mine to work WITHOUT that showing up in my device manager.
However, I had a rather difficult time getting the serial converter from BFM to connect on my pc as well. One thing to keep in mind (little tip from the prolific site) is that often these cables have issues connecting (code 10) because they are cheap knockoffs and don't carry authetic chips from manufacturers of the drivers. Check ebay, same looking cables as you get from BFM are on there for 5 bucks - these cables retail for 25-30 from a store. So after I spent 6 hours trying different drivers all over the web with no luck, I went out the next morning and bought a USB to serial cable (it was called a USB to PDA) from best buy which worked with the prolific driver that came included on a disc with the cable. Granted, it was 30 bucks. Now I'm not sure what made things work. If it was the specific driver (looks to be the same prolific 2303 driver that comes in the BFM driver pack) or the cable itself - I never tested the BFM cable afterwards.
I'll try the old cable I got from BFM later to test if somehow the drivers I got were the trick. If so, I'll upload them and make them available. Otherwise I'd recommend just heading to the store to buy a legitimate converter.