So i was on my way to install the bought led in the aquainlet reservoir, these are the 5 mm led aquacomputer sells.
So i stripped down the wires, and noticed there is a resistor installed on the power line.

Furthermore the power line was wired to the 12V 4 pin molex power line.

Question is, i am getting a LED from somewhere else, and this LED is has a specification of say 2-2.2V, and if i wire it to the 12V power line, i need to install a resistor on the power line that will reduce the voltage from 12v to below 2.2V, otherwise the LED will burn, right?
Likewise, if i will wire it to the 5V power line of the molex connector, the resistor would have to be a lighter one, becasue the reduction from 5V to 2V would be lower than the reduction from 12 to 2V, right ?

This resistor would have to be soldered only on the power line, and not on the ground line, am i getting this correctly ?

For those of you who want to know the answer to this question, i found a very easy eexplanation on how to do this here.
http://www.gtsparkplugs.com/Dropping_Resistor_Calc.html

Now you can use what ever LED you like and wire it the way you like it.