if its not crowbaring the power supply it will be fine, as far as protection you want to throw a diode across the solenoid ( cathode to + side, anode to - side) so it wont spit out back EMF on your power lines causing spikes and noise
otherwise your arduino's voltage regulator might run a little warm, but it should be fine as it has protection in the IC
Thanks for the info - any ideas on the spec of the diode? or maybe a part # for me to look into?
Not sure if I need it since I am unsure if this is better than the simple Voltage Regulator on the arduino?Would it be worth putting this inline?