The ATEN UC-232A USB to RS-232A Adapter
This device is also sold as the "IOGEAR GUC232A USB to Serial/PDA Converter Cable" and the "Tripp Lite U209-000-R USB 1.1 Serial Adapter".
This device claims to be compatible with Windows XP, but we have had reports of it being extremely unreliable. We do not recommend using this device and cannot offer any technical support.
However, if you have one of these already, you might try installing the latest drivers which can be downloaded from the manufacturer's websites. You might also try contacting their product support department.
Manufacturer's home page: www.aten.com
Manufacturer's home page: www.iogear.com
Manufacturer's home page: www.tripplite.com