Unless it comes free, I would not bother with an internal card reader, especially not a USB2.0 one. A good external card reader (still only £20) will be faster, and USB3.0 versions will help for the future now that cards are hitting (and maybe exceeding) USB2.0 speeds.
Power supply is a critical component in terms of reliability, 450W is more than enough, but it's important to get a make/model that is known to have good quality output and components.
I'm not convinced it's worth getting another dedicated graphics card given that you have an OK one built into the CPU. Photoshop doesn't require a beefy GPU to be able to accelerate processing, CPU speed is far more important. Worse is that the dedicated card you have chosen is only a little bit faster, so it's not really worth it
IMHO. (see
http://www.xbitlabs.com/articles/gra...raphics_6.html)
What company are you using to create the builds? We might be able to play with the configurations for you.