The graphics card will be a massive increase.
DO NOT BUY a 500watt Rosewell power supply if you like and want to keep your computer. They are pure garbage. known to blow and kill other components with it.
Post a budget for the power supply and we will post a much better supply in your budget.http://hardocp.com/article/2009/02/16/entry_level_power_supply_roundup/14