Can I upgrade the Radeon HD 6490M series "graphics card" (with only 512 MB versus 1 GB on the Radeon HD 6750M) on a Samsung NP700Z5B-S01UB laptop? Or can I run an axiliary graphics card? I am not certain if I have an external PCI slot for running an auxilary graphics card or if I can rig up a connection? I wish I at least had the slightly better Radeon HD 6750M. Would the Radeon HD 6750M or something better be able to fit in the laptop?