MarkT:
That link is to a MOSFET that is nothing like the RFP30N06LE - it has a max drain current of 0.2A rather than 30A, an on resistance of 1.4ohms not 0.047 ohms, it requires 10V of gate drive to turn on properly (not 4.5V).Having said that they function the same way except the surface mount one is underpowered for that load (the max drain current is not a value you go near in practice for continuous use - its usually the point at which the device is running as hot as it can with maximum heatsinking. For switching 0.15A go for a surface mount FET with about 0.5 ohm or less on resistance ideally - or at least a drain current rating of 0.5A
If the 12V light is a tungsten filament bulb it will draw about 1.5A at turn on if its 0.15A at temperature (the resistivity of all metals increases with temperature). If an LED it will just draw 0.15A.
You want a logic-level MOSFET anyway (Rds(on) quoted for Vgs=4.5V, not Vg=10V)
Thanks! I'll reread that a few times to try to digest it, but I think that tells me a little more about what some of those numbers are and what they mean. I'll post again when I find something that looks like it might be closer to what I'm needing.