If I buy an Intel 17-2600K, which has superior graphics to the non-k model (I am not into overclocking) do I need a separate graphics card at all? I do a lot of photo editing in Lightroom and Photoshop CS5.
Photoshop does have some GPU acceleration features but unless you are editing video the integrated graphics on the 2600K should be just fine for your stated uses. Adding an SSD is something you would benefit from.