As you want to work on Windows Vista then you have to buy faster and more expensive computer to run more smoothly you need to buy Intel Core 2 duo processor and almost 2 GB of RAM as you like digital photography and photo editing and this application are more high-end so even you can plan for purchase of graphic card for your new computer and the core 2 duo processor are more expensive as compared to older P4 CPU and for XP 1 GB of RAM is enough to run the system effectively but for Vista you at least need a 2 GB of RAM to work more smoothly and some latest motherboard come with integrated graphic as well as sound card and the motherboard and the RAM are available more cheaper only you have to spend more on CPU and Video card the Video card price depend on which brand you are purchasing and how much MB of memory you are purchasing.