Is three fans enough?

[MetallichicA]

My friend recently built a computer. He's got an AMD Athlon 2100XP, and the heat sink came with it. He has three fans already in his case.

So here's the problem- apparently the temperature in BIOS (? I didn't know you could read it there- learn something new every day) reads 160 degrees. I guess he's going to put a fourth fan in now to try and fix that.

He's not overclocking or anything like that, he just has a basic computer. He also has a GeForce3 with a fan on it.

What's going on with this? It shouldn't be that hot, right? And how can he fix it?

Thanks


p.s. Would anyone recommend liquid cooling? Not necessarily for his computer, but we'll be building one soon, and we're wondering if it's worth having to install 4 fans, or if liquid cooling is enormously expensive, or what. I know absolutely nothing about it, just heard of it.