Hey,
I have a Sony Vaio Laptop Model: NW-240F.
I want to replace/upgrade its graphics card. Can I do it?

Plz help

only if its a removable graphics device will you beable to upgrade it ,most laptops video device is soldered to the motherboard .usually only in highend gaming laptop will you find removable video device ,im guessing you are going to be stuck with what you have ,the : Intel Graphics Media Accelerator (GMA) 4500MHD.
its intergrated[not removable ] according to this site
http://www.notebookcheck.net/Intel-Graphics-Media-Accelerator-4500MHD-GMA-X4500MHD.9883.0.html

Upgrading or replacing any sony laptop stuff with non-sony gear is an exercise in futility. Don't bother trying.