Just make sure you don't send it through the scanner until there is nobody between you and the magnetometer. How not to get your computer stolen:

1. Remove all metal, shoes and belt from your person so you don't get stopped and scanned yourself.
2. Wait until the person ahead of you in line gets safely through the magnetometer.
3. Send computer through scanner.
4. Walk through the mag yourself briskly.
5. Be there to meet your computer as it comes out the other side.
6. Secure computer in bag, then put your shoes, belt, etc. back on.