Laptops use a Mini PCI slot for their graphics cards I believe, Desktops either use PCI, or PCI x16 for theirs.
What some people do is get an adaptor from Mini PCI to PCI/PCI x16 and plug the graphics card in outside of the laptop.
This however limits the performance of the card as it does not really have the correct bandwidth etc.
Also, your power supply in your laptop will in most cases have not enough power, and will not have the correct plugs, as most of the Graphics cards now are not just powered from the Slot.
In short, its probably better to keep your laptop as it is, or get a desktop