I'm looking to run a PCIe and a PCI card in the same PC but I want to estimate the power requirements as I only have a 300W supply at the moment. Apparently there is a web site that gives this kind of information and allows you to interactively check different hardware setups. I've tried looking but can't find it, has anyone come across this site?

Try this:http://www.extreme.outervision.com/psucalculator.jsp

Thanks a lot that was really helpful.