If you are going to get an SSD, save up until you have one large enough for the OS.
One of your samples sells for about $80; you can get a basic OS SSD for $40 more: http://www.tomshardware.com/reviews/ssd-recommendation-benchmark,3269-3.html
The advantage of an SSD is not for data. For movies, music, and other data, since they play at a rate slower than the transfer rate of an HDD, there is no benefit to putting them on a faster drive.
The main advantage of an SSD comes when you install your OS on it, and your games with the slowest-loading levels. You get snappier system response, and those levels load faster.
A cache SSD will not cache your movies, and probably not your games. It will mostly be filled with your OS. So you should just save up for a regular one. One big enough for your operating system, plus your favorite games with levels that you wish would load faster.
If your system is fast enough to satisfy you, why not just buy another HDD to increase your storage space? If you put in an SSD you will have to install your operating system, games, and other software all over. Some of us are comfortable with this procedure, some are not. It can be a lot of work.
Finally, only certain motherboards support caching and I don't see it as a feature of yours. I have a low opinion of software caching on other motherboards.