This may result in only partially turning on the transistor, causing it to overheat and possibly be destroyed. There are several ways to add another transistor to solve this problem. If I can find time, I'll e-mail some alternative circuits to you. I may even go with a minature relay. When you inject a current into the base, that current is multiplied by the beta of the transistor.
Beta is always low when the collector nears saturation.
This means you will need 15 to 30 ma of base drive to control your lamp. This could be done with a lower value pullup resistor, but the problem is that the LM339 turns off the transistor by stealing current from the base drive. In doing this, it has to pull the base down to no more than 0.5v above ground in order to ensure complete transistor turn-off. The LM339 will only reliably sink about 5 ma with 0.5 volts on its output. If you try to sink more current, the output voltage will be higher, and some current will go to the base of the transistor.