You say he is upgrading soon, so it wouldn't be a waste of money buying Guild Wars 2 since he will buy it anyway when he gets a new computer (lets pray to god its not another crap Mac).
In any case, I would bet towards that video card NOT working.
EDIT: If you use this chart:
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.htmlyou can see the 9400m is in the same hierarchy as the "Integrated: Intel HD Graphics 3000" which is the LOWEST required spec for GW2 so it might work, but in the lowest of lowest form.