You can run it, but don't expect good framerates. What you need is a stronger gpu such as the ones suggested by firo40. I'd recommend a r9 290 since it's starting to fall down in price and should be cheaper than a gtx 780. It's also a little faster but it varies from game to game.
Also I'd recommend going with Windows 8.1 as it has longer support and you should see some performance improvements, atleast in newer games. Windows 8.1 will have a start button soon, but until then, check out this: http://www.classicshell.net/