I don't believe it makes sense to base the decision on brand. I think the particular type and revision of chip and driver is what is important, and the chips can change within one brand or even one marking of the "cable" quite easily (not to say that there is little control over the drivers themselves).

If you can mine out some data from Win about the virtual COM, FM could detect if a "new cable" has been used, and you could throw a window asking the user to send the data to you, asking him also for a comment if it is "go" or "nogo". I believe most users are willing to help you with this. The window and data should be displayed also to the user on a click on some menu item; so if a "known good" cable is identified, he can try a cable before he buys.

Unfortunately I have no idea how much info can be collected from Windows - it's useless if at least the type of chip (and perhaps silicon and firmware revision) and version of driver cannot be determined unambiguously.

I found out that there are many revisions of the Prolific chips, making the picture more complicated than just the 3 suffixes (X, H and HX). For example, the current datasheet of 'HX says "revision D", but what I have is apparently revision A (the datecode ends with "3A").

You might also want to ask Prolific for help...

Jan Waclawek