Laptop graphics cards resolution

[Valor]

Thinking about buying a new laptop, one thing I want to make sure is it can support an external monitor- Dell 30" - at its maximum resolution of 2560x whatever. How do I find out whether the graphics card bundled can support that?

For example, in a machine I customized on Dell, the graphics card is the Geforce 525M, but when I go to the Nvidia page for that card, it doesn't tell me what the maximum resolution it can give on an external is

I know MacBook pro's can support that resolution, so maybe they are the way to go..

Thanks