No laptop will run After Effects with performance adequate for demanding jobs, but the computer that you mention will run After Effects well enough for simple jobs---or for demanding jobs if you're patient and careful about how you set things up and work. The most limiting factor will probably be the single hard disk.
See this video for a discussion of the various components required to run After Effects and how each contributes to performance:
I use a wimpy MacBook at home right now for a bunch of CS5 and CS5.5 projects because my personal MacBook Pro was stolen a few months ago, but I don't render with this laptop unless there's nothing else to use because it takes too long. This weekend, however, because I have something that must be delivered on Monday, I'm doing some fairly heavy motion graphics projects on the MacBook. I expect it will spend most of Sunday rendering.
I also use all kinds of other machines because I freelance at several locations. Some are spanking new powerhouse systems, some are very old and weak by todays standards. Here's the deal with AE. You can run it on minimum systems but you have to live with renders and ram previews take a while. As long as you're careful you can do about anything you want, it just takes more patience.
The more horsepower, the more productive you'll be. There comes a point where throwing more money at a more powerful system may not be cost effective. Your workload, workflow, delivery deadlines, and the value you place on your time will dictate your budget. I've taught classes where the students were high school freshmen with no jobs and very minimal systems did amazing work with AE because they put in the time and could live with the processing times. Only you can decide if throwing more money at a more powerful system will be worth it. As Todd says, if you're careful you can do just about anything you want on that laptop.