The spec sheet does not indicate anything that can be upgraded beyond wireless mini-pci and bluetooth card.
Axiom and MXM do not co-exist, their interfaces were specifically made to not support each other's cards. Dell uses Axiom on some of it's high end laptops from 2006 and later. This does not appear to be one of them. Dell has also applied the name to a drive interface since then.
Start by looking for mxm upgradable laptops http://www.mxm-upgrade.com/
And rest assured a desktop is the more reliable way to be able to upgrade your graphics card.