I need a laptop for programmes. Anyone know any good ones?

I'm going to buy a laptop for programmes like adobe flash player, photoshop, and sony vegas. I need one fast enough to handle them with no lag or anything. I would also want one with windows 7 already installed. I'm only planning to use it to make youtube videos and brows the internet. My budget is: 400 pounds. Which is 649 dollars in US currency. Anyone know of any? Links and names would be appreciated. Thanks! :)