disagree on the 7750 won't photoshop well:
Article below shows that once you get about $100 worth of card, extra gpu budget does not result in significant extra photoshop performance. .
http://www.pugetsystems.com/labs/articles/Adobe-Photoshop-CS6-GPU-Acceleration-161
But I do think you can get a 7770 for a very minor increase over the 7750, and offer greater gaming performance (and perhaps minimal photoshop benefits).
It will potentially require a fan (if you were sent on a fanless 7750 for a silent pc).
I would agree that I would get the standard drive over the green drive. They are about same price, and the standard model drives do not waste significantly more energy or noise over green drives anymore.
Speed is not a concern, as i assume you'll use the SSD as your active workspace, and the HDD just for inactive storage.
You may want to consider a 256gb ssd, and then a single 2TB HDD drive.
If you wanted backup, do realize that even RAID1 only protects from disk failure, and won't save you if your house burns down.
In this day and age with the internet, it is feasible to afford and do off-site backup to the"cloud" instead which will also save you from physical destruction.
But yea, if you wanted to keep it local and you don't have good internetz, RAID1 i suppose.
I think the psu is fine, seasonic is a top tier psu company, so their wattage ratings are true. although you can get a slightly more powerful one for not much more. If you have a beefier PSU, then it will be running at a lower load% most of the time. Doesn't make a practical difference, but it will mean that the PSU won't have the fan on all the time.
A 600watt PSU running at 30% load will likely be silent, versus a 300watt specced PSU at 80%.