The intel core 2 dous are the best proccessors right now on skt lg775. AMD's x2 are still pretty good if you must go with AMD, but a core 2 dou e6300 oced a little beats an fx-60 with a $400 difference in price
. And yes i would go with a dual core, cause its more future proof and its great for multi-tasking (ie listining to your mp3 files and photo editing at the same time).
If you give us a budget, we should be able to come up with a computer for ya. Do you need everything (monitor, keyboard/mouse, speakers) or just the computer?