Comparing ATI graphics cards 550v and 5730

I am buying a laptop. The two systems I am currently considering have different GPUs. ATi Mobility Radeon HD 5730 and ATi Mobility Radeon HD 550v. Otherwise, their specs are almost identical. Is one of these cards objectively better than the other?

Portal 2 requires ATI Radeon X800 or higher. Are the cards I am considering "higher" than that?

Reply 1 : Comparing ATI graphics cards 550v and 5730

http://www.google.com/search?hl=en&source=hp&q=notebookcheck+gpu+comparison and it's first hit has the 5730 and 550 for you to compare the results.
Bob