That's not a lot. Less than 6.5 GB per day. I'm not sure how much WinRAR and Photoshop's swap files would count into the total but you probably won't hit 20 GB per day.
I think for home use patterns, we should be get about 3-5 years of life from the SSD... maybe even more. And if you get a larger capacity SSD, the lifetime generally increases since more cells would be written on before a rewrite cycle, unless of course the SSD is already filled up. I was reading up Anandtech's writeup on the SSD lifetime. If you run the SSD as a database storage (aka SSD killer), you still get about 1-2 years of lifetime from it.