Needing to test out computer

Hi, I just got a pc from a friend. To my knowledge it has a Pentium 4 2.8GHz and 2 gb of ram with a 500watt power supply. Not sure if it works though, whenever I turn it on it makes this strange sound and the cpu fan barely spins at all (its obvious the sound is the fan) All I want to do is make sure this computer works, and will post before I go out and buy a cpu fan for it. Is there any way of going about this without damaging the computer? Any help is appreciated.

Thanks

first thing i would do is connect a monitor to see if the motherboard POSTS; look for any errors on startup. there is the possibility that the power supply needs to be replaced but if you can verify the processor needs a new cooler i would look into swapping that as well.