You can use the 120GB SSD but you don't want to install any more than you have to on it. Some forum members have suggested the OS and your 1 or 2 favorite games on the SSD and everything else on the HDD. Others suggest getting a 256GB SSD. I have a 120GB SSD running Windows 7 and install everything other than the OS and MS updates on the secondary HDD.
Hope this helps.