It's very simple to get the answer to your question if you bother to visit Apple's website. Click Store/Customer Service/Post Purchase.
You can read the refund and exchanges policy right there or select this link:
http://www.apple.com/support/store/postpurchase.html
Here is the text or their policy:
RETURN & REFUND POLICY
If you are not satisfied with your Apple purchase of a pre-built product, please call 1-800-676-2775 for a Return Material Authorization (RMA) request within 10 business days of the receipt of the product. If the item is returned unopened in the original box, we will exchange it or offer you a refund based on your original method of payment. The product must be returned to the Apple warehouse within 10 business days of the issuance of the RMA. All products must be packed in the original, unmarked packaging including any accessories, manuals, documentation and registration that shipped with the product. A 10% open box fee will be assessed on any opened hardware or accessory. If you purchased your order using an Apple Instant Loan or an Apple Business Lease, you may be asked to provide a major credit card (Visa, MasterCard, American Express, or Discover) for Apple to assess the 10% open box restocking fee.
Please note that Apple does not permit the return of or offer refunds for the following products:
Product that is custom configured to your specifications
Opened memory
Opened software
Electronic software downloads
NOTE: Apple recommends that you (1) use a carrier that offers shipment tracking for all returns and (2) either insure your package for safe return to Apple or declare the full value of the shipment so that you are completely protected if the shipment is lost or damaged in transit. If you choose not to (1) use a carrier that offers tracking and (2) insure or declare the full value of the product, you will be responsible for any loss or damage to the product during shipping. Please note that the United States Postal Service (USPS) offers limited tracking capabilities and that there is a 30-calendar-day waiting period before the USPS will initiate a trace.
FINALLY-don't wait around beyond the time limit and then get bent out of shape when you can't return your product. If you are beyond the time limit, you may still be able to return your product as long as you ask nicely and a reasonable tone. Apple has been very helpful to me and my customers in the past if you ask them nicely and plead your case logically.
Hope this helps...
