I’m guessing that a PNP/pMOS transistor would accomplish this far more effectively than a reed switch of greater complexity. The PNP/pMOS transistor performs a logical inversion – thereby switching off when the reed switch is closed (conducting), and switching on when the reed switch is open (“off”).
Sparkfun (and every reputable electronics supplier) carries both.
PNP Bipolar-Junction Transistors: https://www.sparkfun.com/products/522
p-Channel MOSFET (pMOS): https://www.sparkfun.com/products/10349
the MOSFETs are better for higher current applications, but (speaking only for myself) are more slightly less intuitive for a beginner.
