Yeah, sounds like a nice upgrade, but remember that you bought the entry-level MacBook for $1100. You're now looking at the mid-level for $1300.
That means you'd have a price difference of $310 + taxes for an extra GB of RAM, bigger HD and faster processor.
The memory and HD only come up to about $130. So is it worth the extra $180 for the faster processor for you?
Now, if you can get your local Apple store manager to waive the restocking fee for you, I'm sure it's possible, then I'd definitely say go for it.