I bought an iConcepts Serial-USB bridge in 2002. The driver was never stable until I finally found this one updated at Prolific in Dec. 2007
The iConcepts device inside the plastic shell is actually reported as a Prolific device in my Windows XP device manager. Below are the details.
This is a more friendly XP driver from the Taiwan Manufacturer site for PL-2303 USB to Serial Bridge (H, HX, X) Installshield Driver Setup Program
v220.127.116.11 for Win98SE/ME
v18.104.22.168 for Win2K/XP/2003 (XP Logo Certified)
For Prolific USB Device VID_067B&PID_2303 device only (check your control panel hardware COM port device ID that gets added by this driver PROPERTIES/DETAILS reports in as a USB\VID_067B&PID_2303, a generic device sometimes marketed as a iCONCEPTS product around 2002