It's a giant question of "it depends". Laptop GPU's are a standard
mini-PCI express connector
MXM PCIe connector. There are four or five different connector types so you have to match up the ones you have. Also laptops have a limited power supply and thermal dissipation capacity. Just inserting a stronger GPU may result in the laptop being unstable either too much heat or not enough power. For these reasons you should only do this if you know exactly what your doing.
This is the website to go to about buying MXM GPU's and how to install / upgrade them.http://www.mxm-upgrade.com/
Had the name wrong, Mini PCI-e is a different type of connector.