Im updating my system and having been looking at tons of reviews and videos on youtube. And the truth is an SSD is about 10x faster than an hdd. I am going to buy one. The only problem is the price. Thats my opinion, but I recomend you see some videos on youtube.
I'm wondering, what exactly is best run with the SSD. Like of course windows will be on the SSD. But like would programs also run on it? and like if I installed a program onto the other harddrive, would it be just as fast (probably not, but just doublechecking)
I'd recommend dropping the 500GB drive from your build list and instead replacing it with a SSD (40-80GB). That will cost you a little over $100, depending on what you get. The OCZ Vertex series is a very good choice.
As far as what to put on the SSD, since your space is relatively limited stick to things that can benefit from the faster drive, such as the OS and programs that you load frequently. Avoid filling it with music, videos, pictures, etc. because they typically do not see much benefit from the faster drive compared to the improved load times of programs. And they take up a ton of space. Use the 2TB drive for those.
The drive you linked is also a good choice, but its advantage is only available when used with SATAIII. If you have a SATAIII motherboard, go for it, but otherwise you will actually be getting worse performance than the OCZ drive while paying more.
Regardless, your write speeds will be substantially worse on the Crucial drive but it's pretty widely accepted that read speeds are more important (for the most part), so this is not a big issue.