Hard drive failing, what files besides photos/music/etc should I back up before replacing the drive?
I bought my MacBook 5,2 Intel Core 2 Duo 2.13 GHz 2GB 800 MHz DDR2 SDRAM in 2009, never had any problems with it until now. For a few months now, my macbook will freeze up (usually if I'm doing a lot such as posting a youtube video on facebook, or running a game,etc) and make a clicking sound, to which I can't do anything except hard restart it. It only did it once in a while until now it's happening more frequently at very annoying times. I never thought to look it up because I'm an idiot but now that I did I learned that my hard drive is imminently going to fail. I know I dropped it once, from my bed to hardwood, with no immediate damage but I'm sure that could've done something, other than that I take very good care of it.
So I'm in the process of backing up my stuff, which I figure isn't a lot so I'm probably going to use a USB drive & CDs..but my question is: Is there anything important that I need to back up besides my files (pictures, music, documents)? Like any program files etc? And when I do replace the hard drive, which I may do myself following DIY on here, what will remain on my computer? Will my applications all be there? I've only downloaded a few programs that could be redownloaded anyways (frostwire, tinyumbrella, etc) and my Pages/office are on disk. Sorry if these questions are stupid, this is my first personal computer and I've honestly never had to back anything up before/replace hard drives. I appreciate any help to any of these questions and I can further detail anything needed
MacBook, Mac OS X (10.6.8), 2.13 GHz Intel Core 2 Duo 2 GB DDR2