This is my first experience with Linux, and the person who sold me the computer won't answer my emails. I have a Dell Inspiron 531, running the Linux OS Ubuntu 12.04, and i need a USB wi-fi adapter that's compatible with it. Two different stores have sold me adapters they said would work, but neither of them has. Can someone who actually KNOWS tell me what USB adapters(s) is/are compatible with my system? Thank you.