Arduino used to control other devices via USB

In a remote past i made an home automation project with a PC always on connected to some USB devices that can control some realys....

Something like this.... http://www.ebay.it/itm/USB-Relaiskarte-mit-8-Relais-PC-nach-I2C-Adapter-/360253432923?pt=Mess_Pr%C3%BCftechnik&hash=item53e0c7245b

Now, i would like to use arduino to manage the same usb devices....

Is that possible with the board like this http://www.ebay.it/itm/Arduino-Compatible-Uno-Rev-3-0-development-board-with-free-USB-cable-/130834098036?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e7651e774

and this http://www.ebay.it/itm/0616-Arduino-USB-2-Serial-Converter-Convertitore-USB-Seriale-/200755733083?pt=Componenti_elettronici_attivi&hash=item2ebdf9625b

or maybe i need something different?

Probably easier to use a standard arduino and basic relay boards like below.

http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1311.R7.TR8.TRC1.A0.Xarduino+relay&_nkw=arduino+relay+8&_sacat=0&_from=R40