fans plug in using the same molex plug as a cd drive, just need a spot to mount it. The 80mm are smaller but louder, the 120mm are larger but quieter and move more air(trust me mine sounds like a jet). Depending on the case you have, it may be a case of opening it..clipping in the fan..connecting power. Or opening it..drilling some holes and cutting a grill for airflow..mounting it and connection the power. Thermaltake make very good case fans with a controller and temp sensor to quieten down when cold and speed up when hot. try to avoid cheapies imho as they are noisy and have nasty bearings (tend to fail) Water cooling on the other hand is alot harder and a fair bit more expensive. Unless your planning on overclocking massively its not usually needed
