If we assume:
The computer (including 4th fan and speaker) is drawing 250 watts.
The CRT is drawing 200 watts.
The fluorescent bulb 20 watts.
For a total of 470 watts.
This means with 120v, you're drawing just under 4 amps. Assuming you're on a 15 amp circuit, you've got to have a fair amount of other stuff on it to pop your breaker.
If you're drawing 500 watts, and paying 20 cents per kilowatt, it costs you 40 cents per hour to run this rig. If you run it 24/7 for a month, that's almost $150 of electricity.
I took the highest numbers I could find and rounded up. Your computer will draw less power when idle. So your actual usage will probably be less. Unless something overheats, you shouldn't have a problem. You're not drawing too much electricity for the circuit.