Power supply wattage?

There are few very detailed and accurate PSU calculators.. Like the one available at the antec official website (www.antec.com).. Btw, a good 650W PSU should be adequate for your current setup and will have headroom for any future upgrades (a true quad core, and/or a more powerful video card etc.).. Check out the Corsair TX 650 and the Antec EA-650.. If you've the budget, you may straight away opt for a 750W PSU.. I'll recommend the XFX 750W Black Edition in that case..