EDIT: Thanks, retrolefty, I'll switch them to 10k. How do I determine the right resistors to use for a given power source?
It depends on the current capabilities of the voltage source. The total current flow is simply I = E/R where R is the combined series resistance of the two resistors, so the higher their value the less current they draw from the voltage source. Again any two equal sized resistors will form a voltage divider that outputs 1/2 the voltage source, so just for learning purposes the higher the resistor values the better if it's just for learning purposes.
Lefty