How To Configure your USB to RS232 Cable
See lots of people have trouble installing and configuring these devices.
I've installed several of them for myself and friends and this is coming from memory.

1) Insert the cable/adaptor and Windows should detect it (may have to connect powered receiver if it doesn't detect it otherwise)

2) If your unit came with a disc, insert it when prompted for the drivers.

3) Once completed go to Control Panel, then System, then Hardware, then Device Manager.

4) scroll down the list of device types and find "Ports (Com & LPT)" and click the [+] to expand the list

5) find your cable/adaptor name in the list and right click on it and chose Properties.

6) In here you want to do 2 things.
First select "Port Settings" tab and change the "Bits per Second/Baud" from 9600 to 115200. (leaving at 9600 works but is super slow)
Second select "Advanced" button at the bottom of the Port settings screen and this is where you can select a new Com Port.

Your now done. You may need to reboot the computer for all settings to take complete affect.