LED Resistor Placement Question

[TheOnlyOneHeFears]

This is probably a stupid/basic question, but it's really confused me for a while.
Say you want to hook up a 2.5V LED to a 5V supply. You obviously need a resistor (I think its around 330 Ohms). But where do you connect it to on the LED? Instinct would tell me to connect it to the anode, as conventionally, current flows from positive to negative, thus the resistor on the anode would decrease the voltage going into the LED. I've seen some guides/diagram gurus putting the resistor on the anode. HOWEVER, I've also seen guides putting the resistor on the cathode. The grab bag of LEDs I bought yesterday from Maplin also had a diagram on the back which had the resistor connected to the cathode.
Basically, I'm confused. Conventionally, electricity flows from positive to negative, but it actually flows from negative to positive, right? But LEDs only glow when they're hooked up in one direction, as they are diodes.
So, which leg do you connect the resistor to?

[bgnome]

i dont think it matters. the resistor is current limiting and the current doesnt go any faster through half the circuit if everything is in series. the current in the circuit will be determined by overall resistance.