Ordered Wrong Mouse with 27" iMac - Can I Exchange?

I just received my new custom-configured 27" iMac this morning (totally thrilled as I'm a former Windows user) purchased online from the Apple store.

As I unpacked my gear, I found that I screwed up my order and ordered the standard wired Apple Mouse rather than the Magic Mouse. I must have simply clicked the wrong check box when ordering.

Will Apple do an exchange for me? Can I visit my local Apple store to exchange? Thanks for any input.