We need more information, which processors are they? I think the 2.8Ghz dual core would be better as I've heard the game doesn't use more than 2 threads, but if it's a Pentium D than it's just plain garbage the the Phenom X3 will perform better.
That one in your link is still integrated graphics, and because of the graphics you'd be playing the game on low and a possibility it would still lag. I'm not to sure how it'll run on integrated graphics. Of course you could always add your own graphics card to that computer.
Oh dear...Integrated graphics will be your downfall if you're attempting to play SCII, even if it's the 4200 Mobility. (I'm posting on my laptop with a GMA X3100, which can run it, but it's not pretty.) I would personally suggest that you build your own computer, but if that's off the table, then you should be able to add a graphics card. I'm a fan of the 4870, which you can still get used on eBay. I'd guess that most would be relatively trustworthy as they are often sold when people get upgrades. However, I'm no expert on the subject. It depends upon preferences as well as budget.