cost of returning the original laptop removes any price advantage you may be seeing.
Unlikely that the store would accept the machine back now that you have purchased and used it, without charging some form of restocking fee.
I would stick with the Pro
I started shopping around for a new laptop a couple weeks ago and finally decided that I wanted a Mac, even though it was more than I wanted to spend. When I saw that MicroCenter had an instant $200 off on the base model MacBook Pro, I immediately picked one up. Now, I'm having second thoughts and wondering if should pick up a refurbished 2.26 GHz MacBook from Apple instead. There's about a $250 difference in price between the two ($1060 and $805, after tax).
I know the older model MacBook would be more than adequate for my purposes (web, email, basic Office work, watching movies, etc.), but I'm wondering if the updated features and extra power of the Pro is worth the extra money?