Do what I did...
I got my MacBook from Best Buy shortly after Christmas. They were having a special -- two years of interest-free financing. Unfortunately, I got in a day after the offer expired.
Fortunately, they had just started an 18-month interest-free financing thing.
[They very frequently have specials like that.]
I put down some cash I'd gotten for Christmas, a little bit of extra spending money I had from my last paycheck, and put the rest on my wife's Best Buy credit card. Got the MacBook and an extended service plan.
Minimum payments are $10 a month. I've been putting down at least $100, except last month I only put down $10 because of a very brief financial crisis (basically, due to wacky circumstances, my wife wasn't going to get paid during the month of September). As of now, I have maybe $300 left before it's paid in full, and not a cent of interest.
(Aaaaaand...not to mention that the money I put down on it at first was actually on my Visa check card, so that gave me a couple thousand Visa Extras points, plus the Best Buy Reward Zone thing...pretty sweet deal, if you ask me...)