When you are a photographer with a reasonably advanced camera these days, you will be used to RAW files larger than 10 Mb per file and if you go into shooting video you may even have files larger than 1 Gb. Editing those files quickly requires good hardware. People only used to go for clock speeds of CPUs a few years ago, while they now mostly look for how many cores a CPU has and how much RAM the computer is equipped with. While the approach has improved, most people are still not aware, that the harddisk remains the one factor that is the prime reason for slowing down everything, just as it has been for many years now.
People invest 2000 USD in a new computer, but they remain reluctant to spend 300-400 USD on a really good (not standard off the shelf) SSD. So they make do with a 5400 or 7200 rpm drive which is then the bottleneck for everything they do. A fantastic CPU, a top of the range graphic card, plenty of RAM, however, all of them running kind of idle, because the harddisk does not supply the data to process fast enough.
A really good top of the range SSD can give you totally unexpected performance on your computer. I have had a “mediocre” laptop and just for the change of the harddisk to a top of the range SSD it transformed into a powerhouse with a performance I would never have expected. It is still doing well on most tasks in 2012 despite the other hardware being something like 2005 standards. The one lesson learned is not to believe marketing “experts” but to take the harddisk matter seriously. In terms of numbers, I would not be shy to spend at least 20% of the total of a computer on the primary SSD harddisk.
If you want to find the SSDs that are not just off the shelf, you can check FASTESTSSD. You will discover the really fast ones with some solutions that even offer several thousands of Mb in reading and writing speed.