In reading the specs on Dell's site, I couldn't find anything about what the standard Studio 15 ships with for video RAM, but it can be upgraded to 512 MB, for an additional cost, so if it isn't the top of the line for a desktop video card, but it still should be OK for most games.
The main objection I have to gaming on a laptop is screen size and lack of a decent mouse. By the time you buy a decent sized monitor and a real mouse, why not just buy a desktop in the first place. It will be cheaper and easily upgraded in the future.