Any new PC that you can configure with a video card that supports 2 monitors will be OK, given these requirements. Just buy a PC pre-configured with such a card or ask the shop to put it in, if it doesn't already have it.
I want to purchase a desktop that will run two monitors (20 ").
I often work at home and also use the computer for photo editing, research and writing. I have about $1300 to spend. Suggestions?