As long as you have the receipt and it's w/in 30 days and you have all the packing materials, you shouldn't have any trouble returning it for a refund or exchange. If they give you trouble, ask for the manager.
Here's the return policy, from the back of a Best Buy receipt:
"-Your original receipt is required and a valid ID may be required for all returns, exchanges, price matched and warranty repair services.
-We accept returns & exchanges 14 days from the date of purchase on Computers, Monitors, Printers, Notebook Computers, Camcorders, Digital Cameras and Radar Detectors.
-A 15% restocking free will be charged on returns or exchanges of any opened notebook computer, camcorder, digital camera or radar detector, unless defective.
-We accept returns & exchanges 30 days from the date of purchase on the remainder of our merchandise.
-Exceptions to the 30 day policy include: opened Computer Software, opened Videos, opened Video Games and opened Music. You may EXCHANGE these items for the same title if the original is defective. We do NOT accept returns on these items if opened and non-defective.
-No refund on labor or installation services.
-If any item is returned with any of the original package contents missing, the full purchase price will not be refunded.
-Refunds on cash purchases over $250 and check purchases over $100 will be issued by check from our corporate office within 14 business days of return.
-BestBuy.com return and exchange policy may vary slightly from in-store policies. Please see BestBuy.com for complete details.
-See your local Best Buy store for further details."
Sorry if this is a bit off-topic, but I find it interesting that they take stuff back without a receipt and give you store credit, but when you have a receipt and it's over 30 days, they say they can't do anything for you. I returned a bunch of DVDs in December and January w/out a receipt and got credit. But last week, I went to return a DVD for which I had the receipt, but it was a few days past the 30 and the guy said he couldn't take it back or give me credit. Maybe they were just more lenient because of the holiday period, but it would be nice if they were consistent. Seems there's also some luck based on which customer service rep you get.