Thermal Paste overclock

I wanted to ask what thermal paste is among the best in the quality and price. I have a PC with cpu Athlon xp 64 3800 running at 2400 mhz original 2800 mhz and after overclocking a while, that warms a bit more than normal. I wanted to know if I could lower the temperature by changing the thermal paste and then find out what was recommended.

For Base, Artic silver is cheap and is very good!

OK, thank you very much. So will that give satisfactory improvements? Particularly for high temperature?

Many of the talk about heating 4-5 °C.
I personally think that 2-3 °C would be regarded as true profit.