Home Automation: How to activate a relay via USB on Windows to control devices (blinds, lights, etc)

Although it is most economic and versatile use Arduino as a programmable electronic board, so we avoid the known unreliability of Windows, when you want to activate a equipment is sometimes easier to use a USB relay, either because we have a computer that has to be always on, or for other reasons, allowing us to theoretically control up to 8 switches for each USB connector on the same PC. 
I had to replace an old system that used the LPT1 port for controlling a time alarm (not compatible with Win XP or 7) so after investigating it I bought 2 pcs. of this USB-controlled relay  in Aliexpress.

And if we want to control multiple devices there are up to 8 channels (relays) in the same unit, with each relay 10A capacity, so the possibilities are very extended.