|I've noticed (especially with emachines) the fan will spin at maximum speed until the bios takes over. But that's only if it's plugged into the motherboard. If that's the case with yours check in cmos/bios setup and see if there's any control there.|
If it's powered by one of the molex drive connectors there's no speed control.
But if you find you can't do anything to silence it, I doubt you need a bigger fan; you probably just need a different one. I doubt emachine is putting top-of-the-line fans in those things.
You're not really green until you're soylent green.