^+1 Agree, you are probably using CS4 right? if so, you want a lot of ram and you want it fast because multi-layered photo editing in photoshop will chew up your CPU and RAM.
-I recommend getting an "Intel Core i7 920 Nehalem"
-I recommend getting 12GB of 1600mhz Triple Channel Memory" (My recommended Manufactures: OCZ, Corsair, Kingston)
-For Hard Drive, since you need to keep your data archives safe then I recommend getting 2 640GB 7200rpm Hard Drives. Connect them in Raid 1. All your important data will be mirrored on 2 hard drives so if one breaks then you have another.
*NOTE ABOUT HARD DRIVES* The reason I recommended a specific 640GB hard drive was because its made of 2 320GB platters inside. If you want to get a 1 Terabyte Hard Drive its going to have 3 platters of 330GB most likley and is going to be much slower, the more platters means its going to be way slower so if you want terabyte hard drives, I recommend getting 10000-rpm or 15000-rpm ones since the spindle speed will compensate a little bit for having an extra platter. There are high density hard drives but they I am pretty sure they are going extremely expensive at this point in time. (My recommended Manufactures for Hard Drives: Western Digital, Hitachi)
-For your GPU (Graphics Processing Unit) I recommend getting a business grade card) I would get an nvidia Quadro series, since you aren't doing gaming and a quadro is better suited for photoshop and flash and other programs of similar nature compared to a Ge-force. A 200-300buck card in the Quadro series should do fine i think. I am not quite sure about it though)
-For your Power Supply 700watt should be more then enough! I recommend, (OCZ, Corsair, Coolermaster)
-For your motherboard just get an LGA1366 socket type that supports a QPI of 6.4GT/s and supports 1600mhz ram. Recommended Manufactures: (Asus, Gigabyte, Intel)
-For your case just get a Full ATX tower, you might fit it inside a mid-tower also:
Recommend Manufactures
Antec, Thermaltake, Coolermaster)
-I hope I didn't miss anything
-This should total around 1400 dollars. But we can edit what you need and dont need out of the list
-We will get into more specific parts once we narrow down your choices and needs in the computer!