Final thoughts, and warning: So, Windows XP was the OS of choice back when I wrote this post. I have no idea whether this driver works on any newer Windows operating systems, and I have no intention of trying. I'm leaving this driver up, because I said I would in the post; but if you use it, know that you are doing so at your own risk.
I have a USB adapter to serial adapter. I bought it because Sony stopped including serial ports on the VIAO laptops a couple of generations back and I needed a serial port for my Palm, my GPS and for accessing the console port on Cisco hardware. The one I bought is a Micro Innovations USB610A, which is really a Prolific USB to Serial adapter, which appears to use a Realtek chip-set. It works. I like it. I lost the CD.
Between those three companies, you would think I could find a copy of the driver on-line. You see, this is one of those devices that never had a big enough market share to get included with the multitude of Microsoft supported devices whose drivers can be pulled from Windows Update when they are first plugged in. So, I go to the website for Micro Innovations, and while they have drivers for many of their other gadgets this one doesn't have a driver available for download. Next step, Google... I find a couple of posts about the driver, two from the same site, and they give a tip on how to download the driver from the Micro Innovations website. It doesn't work anymore. CGI timeout on the server side. I go back to the posts, and there is a link to an alternate copy of the driver; but I have to register with some site of which I have never heard before last night. Hmmm... Back to Google, Yahoo, Alta Vista... OK, I register. LOTS of annoying ads. Give me the damn driver... They send a confirmation email to the one-time address I created for Johnny Smeg, a 12 year old girl. (If they retained my registration information after I put my age in as 12 they are in violation of federal law.) I use the link in the confirmation email, and they run me through the same annoying ads... Bastards!
Finally! I have the driver for the USB610A USB -> Serial adapter from Micro Innovations and/or Prolific. It is in a file named USB610A.EXE and I will always have it available here for anyone who ever needs it. No annoying registration required.