I never said that the problem is with using only 2 gig of Ram. But, even before Mavericks came out, 2 gig was OK, but 4 gig was better. Here is one such link:
http://www.macworld.com/article/2052602/get-your-mac-ready-for-mavericks-os-x-10-9.html
Also, trying to run other applications under Mavericks will be slow with only 2 gig of Ram installed. Those other apps would have to rely on Virtual Memory to execute, and the more than is the case, the slower they will run (and especially with 5400 rpm drives).
5400 rpm drives are notoriously slow, especially as they get more and more full. Even faster drives can be "problematic", especially with all the stories I've read about folks neglecting simple maintenance and clean up tasks. And, no matter what one does, drives do become more and more worn out as time passes. Prime example: I have an external Seagate drive that I've been using for over 6 years, primarily for backups. About 6 months ago, the 500 gig Seagate drive inside the case stopped functioning. No matter what I did to check it out externally (via software), I could not get it to work. So, based on prior experience, and asking around, I concluded that the drive needed to be replaced. So, I took the case apart, removed the old drive, purchased a 1 TB Seagate drive from Best Buy for only $50, installed it inside the case, and I was up and running. Still am using that external drive today for my backups.
So, assuming the op got his Macbook over 4 years ago, the drive could be "showing its age". Even if it's still OK, a boost to a 256 gig SSD is well worth it, especially if 1) the drive is getting old, and 2) the op is "tight" on disk space. And, the speed difference is incredible!
As for "putting a screwdriver to your Mac", those ifixit guides are excellent! I've known numerous folks that swear by them also. If I had followed your advice, then when the hard drive inside my Mac Pro failed about 5 years, I would not have replaced it with a brand new, larger, and faster drive myself, but instead taken to an Apple dealer and have them do it, and thus costing way more $$$$$ (and losing a great opportunity to know more about the insides of my Mac).
If one is not a DIY person, fine, don't try and repair a Mac yourself. But, I am a DIY person, both with my Macs and other things (like our cars, our home, appliances, etc.). Quite a bit of the DIY stuff I do is not really difficult. In fact, installing memory inside of a Mac is one of the easiest things one can do. Another simple DIY project is changing the Cabin Air Filter inside a car. The cost to have the dealer do it is at least between 2 and 3 times what I can do it for myself.
In actuality, the first thing the op needs to do is see how much space is left on the drive. That is real easy to do. In the finder, single click on the drive's icon, then go to the File menu, and click on Get Info. Beyond that, checking the Console log, etc, is all well and good. But, another thing the op needs is software that can do a better job of analyzing hard drives. The two best ones are Disk Warrior and Tech Tool Pro. Either of them can do things with hard drives to help make them "healthy" again!
