For video and Photo work, you wont notice that much of a difference in your editing.. You will notice a difference in how fast you open programs but in Photo editing and Video, most (read: All) of the work load is on the RAM and GPU.. However when doing video work and you use up the RAM and GPU then your comp will resort to the swap space on your HDD.. this on a standard HDD brings things to a standstill.. Here is where a SSD would be nice.. But If I were you I wouldnt bother with a SSD as a primary hard drive..
1) Video and Photos take up a shit ton of room and having to carry a Portable hard drive or even a flash drive all the time sucks..
2) A decent SSD that actually has enough space for your programs, videos, Photo, Music, and all you other shit is going to be really expensive..
3) As I said, you are already running a sick system that will run very well for a long time..
you will notice a difference but the cost vs. performance isnt there for me to say to make the up grade..
My current situation is that I am on a 2 year old HP Laptop that was top of the line 2 years ago.. i7, 4gb RAM, 1Gb GPU, 500Gb HDD and I have my 500Gb HDD almost full and I am going to take out my DVD drive and throw in a 100Gb SSD in place of the DVD drive, use the SSD for programs and OS and then upgrade to a 750Gb HHD for media storage (Music, Video, Photo, Games, Etc) .. Then upgrade to 8Gb of RAM.. and I will have a modern machine.. Almost..
If you could install 2 HDD in a Mac then I would say to just get a small SSD and load the OS and your programs on it, but you will run out of room if you try and use a SSD as your one and only drive unless you drop major cash on a big SSD..