On second thought, it might now even be playable at 1080p with that card, behold, barely playable on low at 720p:http://www.hardwareheaven.com/reviews/925/pg4/sapphire-radeon-hd5450-512mb-review-modern-warfare-2.html
EDIT:FWIW, you could put together a computer that could get a minimum of 60fps at med/high settings at 1080p for $100 more than the one you listed, just a thought.
Yea, well problem is that my friends parents are dickheads and his computer is 5 years old, and well runs mw2 at like 5 fps at lowest settings (he has done EVERY possible thing to speed up his games). And well they wont spend more than $400 on a new computer..
So if you can find a computer $400 or under, that would be great!