If it made that noise after purchase, it should have been returned. Now it probably needs warranty service, except for a single possibility - please continue reading:)
You haven't mentioned any results from running the Apple Hardware Test, nor have you indicated any report in System Profiler's "Diagnostics" so I'm not sure how anyone can help without more detailed information.
However, I can make an educated guess that you have an older model MacBook, perhaps the 2.16GHz model that was produced prior to November (you can tell by the serial number, or by the processor speed), and you have downloaded the EFI firmware update but not installed it because you continually shut down your machine when it tries to install the firmware update. Unlike software updates, firmware updates do not install as part of the downloading process.
Information from the main MacBook Support page:
About firmware updates for Intel-based Macs
You can check your Boot ROM Version reported in the Hardware Overview of System Profiler against the version (probably MB21.00A5.B07) that should be showing after the firmware update has installed.
Firmware updates for Intel-based Macs
Message was edited by: myhighway