Umm, I’m running PhotoShop CS5 Extended with full GL capabilities on a 2.5 year old laptop with 2.6 Core 2 Duo. You are talking about modern hardware, in which case anything a typical LA would throw on it will be fine. Photoshop is not very graphic intense, it mainly takes up your memory, so make sure you get at least 4gb of that, 8 if you wanna run a lot of programs simultaneously and play it safe. Remember, PhotoShop and AutoCAD runs on old windows XP office computers, they have legacy that requires them to work on older hardware.
So honestly, I would go with the cheapest of the 3 you mentioned, I don;t think you will really notice a difference in performance. Spend the extra money on memory, it will be more important for running Photoshop, Illustrator and AutoCAD at the same time. Good luck with the build, hope it turns on the first time!
