If you are buying from Buy.com, you have nothing to worry about. Their customer service is pretty good. If you don't like something, just exchange it. I just did it myself last week. The only hassle is that you will be out of a processor for 1 or 2 weeks. Remember to use the returning coupon & ebate to save even more. Cpu from Buy.com also come w/ 3 yrs. warranty.
I made the mistake of buying from one of those pricewatch store that only have 15-60 days warranty. Didn't read the fine print when I was ordering. No return, only exchange if defective. I was planning to cancel my order and buy it Buy.com so that I could take advantage of that 3 yrs. warranty. Oh well, no loss. I will probably upgrade again in six more months.