So to that end I would like to replace the (I am guessing) 5400 RPM HDD with a SSD and watch it speed up considerably. I don't know where to start with this.

There are few ways to make a laptop faster that are as easy and cost-effective as replacing your existing hard drive with a solid state drive (SSD).

The teardown of the AIO desktop revealed that the SSD and HDD are replaceable, but the GPU, RAM, and CPU are all soldered to the logic board.

From the boot chime to desktop is about 25 seconds tops. I did upgrade from 4gb to 8gb earlier this year so with the SSD I finally have a Mac that runs respectably well for my needs anyway.

Has your notebook's storage slowed down to a crawl? Is it making a racket? Perhaps its time you upgraded to an SSD.