There will be no harm done to your CPU if it runs at 80C under load, it just not optimal. It's like living in the city takes a few years off from your life because of the air/noise/etc pollutions, so it's the same with the CPU, it will live for (warning: random numbers ahead) 15 years instead of 19 (you will be replacing it after 7-8 years max anyways).
However, it's better to have it cooler because if it gets very hot (around the 95-100C), it will limit it's own performance (called "throttling") to avoid damage, and when that happens you are getting less performance from your CPU. A cheap cooler would do the trick as how the others suggested above. The evo212 is far from the best cheap options nowadays, but it will do the job well and it can be found very cheap all around the globe.
my 212 evo but the fan on it started making an annoying rattling sound 1.5 wks ago and I had to replace it.