USB serial converter drivers

I have an aftermarket device that controls some parameters of the computer and transmission for my diesel truck. The device greatly increases mileage, horsepower, efficiency,fun, etc. One of the functions of the device is to read the PCM strategy when it has been reflashed at the dealer. In order to do this i have to install some software on my PC and hook the device up to the PC via USB to update it. I had incomplete info when I first hooked the device up (complete lack of manual and info from distributor- manufacturer is trying to help) and when it asked for drivers, I pointed it to an update file from the manufacturer since that was all I could find. Some of these files may not even be drivers. They end in dot sys, dot ini and dot exe. Since this was in error and I now know where the drivers are and what to install I have tried to correct the error. My computer calls the device a USB serial converter. I have uninstalled it about 10,000 times with the device plugged in and without. I have gone into regedit and found the device and nuked it. NO Matter what I do, it reinstalls with the erroneous files. If I tell it to update drivers, it always reverts back to these bad files. If i eliminate all reference to the files on my computer using the search function, it will just complain that it misses the old files and would I please replace them. It will not accept anything else. Some of you may know any easy fix. I'm not that sophisticated, and have no idea what to do that could fix it short of reloading windows. I use XP pro SP2. My system: AMD Athlon64 3400+,1 gig Ram,ASUS K8V SE Deluxe. I would greatly appreciate any help.
Mike