I have Alienware M15X laptop. 

Used to worked perfectly until one afternoon the games started to "stutter", lag, "move too fast" (in games like TF2 and L4D2 as an example).

Most definitely not my network (I have a low ping, also I called to make sure the isp didn't blacklist any servers, and I checked traffic. Not to mention I have no lag nowhere else). 

I tried turning down all the options (not needed since that very same morning it was running perfectly on high), updating the drivers. Everything. 

I already reset the laptop to factory defaults just in case there was a driver causing this (there wasn't. I didn't install anything new). Didn't help. 

I am guessing my graphics card bit the dust? 

I had a (Vista) ATI Mobility Radeon HD 5730. 

Possible to upgrade? If yes, where can I find a list of compatible cards? Which one is recommended as an upgrade?