I also considered getting a 120GB SSD to use as a cache(?) for the computer. If this sounds like a good idea, I am still open to doing it. Any suggestions are welcome.
I can comment on this much at least.
How did you intend to use it as a cache? I've heard of some people using SSDs for the swap file for their computer, but this may not be as good of an idea as you might expect. For a couple of reasons.
First off the SSD has a limited number of writes that it can survive before the memory cells wear out. Using it as a swap file will shorten its life as the OS pages stuff to it. A 120GB disk would still likely last a long time though, because of the wear leveling algorithms built into the OS / firmware.
The other reason is that you might not really even need a swap file. Depending on what you're doing, you're likely to never even need all of that 8GB of RAM. I never use all 4GB of mine. I could be completely wrong of course, depending on just what you're doing.
As for other uses for the SSD, I've read a number of other strategies for putting them to good use. Some people suggest installing the OS to the SSD to dramatically improve boot times. Some people suggest installing programs to the SSD but keeping data on other storage media, since it will speed up launching programs but keep wear to a minimum.
That might not be so important with modern SSDs though. One thing you might want to watch out for with SSDs though is the limited sustained read / write (especially write) speeds compared to traditional mechanical drives. If you're planning on moving around multi-gigabyte files at any time, I'd suggest you keep them on a mechanical drive.