Can you Run Unix App in Windows 7?

As I was exploring my Windows 7 Ultimate by going into Start>Contrl Panel>Programs>Turn Windows Features On, I noticed a check box that says Unix app in windows. I want to be sure if it is possible to run Unix Applications in windows without installing another OP. I set the feature on, now it is going to direct me to install Unix... Waiting for an answer before I take into consideration of Downloading. I also turned on more features like telnet, TCP/IP, A few games, and some other options...