Based on what I'm seeing of others online the Samsung NP-150's BIOS can be reached via 'F2' while the boot menu (as you know) can be reached via the 'Esc' key.
http://community.linuxmint.com/tutorial/view/390
http://ubuntuforums.org/showthread.php?t=1461860
http://forums.cnet.com/7723-19688_102-602077/does-the-samsung-n150-have-a-boot-menu/