I will spare you the "don't do it!" admonitions since you've already seen that from several people. I just want to warn you to read the fine print on whatever offer you decide to take.
When I bought my PowerBook back in 2003, Apple was partnering with MBNA to offer a 180-day, interest-free plan. Since I didn't want to wait to save up, I jumped on this offer, and placed my order for the PowerBook plus a copy of Final Cut Express.
Unfortunately what I did not realize was that the 0% financing offer was only on the first payment charged to the account, whatever that happens to be. And, given that I had purchased a BTO Mac, the first payment charged was the $150 for Final Cut Express.
As a result I had 6 months to enjoy interest-free payments on $150, but I was forced to pay 28.8% interest on the remaining $2800 that was my PowerBook.
Long story short, this screwed with my finances and I ended up carrying a balance on my credit card -- something I had never done in 10 years and had sworn I was way too smart to ever do -- which I only finally managed to pay off by mid 2006 -- three years later.
So enjoy the MacBook Pro and if you want to finance it, just make sure you know the fine print. Free money is great, but only if it stays free!