Macs are more sophisticated than Windows in that regard. No System Software CDs (CDs?) - there is no CD slot on a MacAir. You simply press the Option key on power-on, then choose restore from a backup over the wi-fi. MacAir's automatically continually back up to external storage so you never lose data. Someday Windows will copy that built-in feature, as they do almost every other feature of Macs.
What? Wow, I have been gone a long time. My last encounter with a Mac was in middle school—an iMac G3 (the slot-loading variety) on System 9.