A CPU cooler is that little round heatsink on your motherboard. Those who choose to overclock their processors in order to gain faster computing will usually, but not always, replace that heatsink with a better one in order to keep the CPU from overheating - which shortens it's lifespan.
has headroom for overclocking, as noted by it's 74° tCase maximum. If you don't OC, then no, you don't need a better cooler.
If you do decide to OC, knowing your CPU temps is critical. You can download many programs that provide this information, my favorite is HWMonitor
. It's free. So is CPU-Z
, another handy tool.