There is a tremendous amount of risk associated with financing anything - your financial situation may be different in a year than it is right now, and you may need the money for something else. Financing is terribly risky for assets that do not hold their value well - for houses it's a good risk (since the house in 10 years will likely be worth more) and for cars it's a reasonable risk (since you need it, and it will be worth at least something in 3 years), but for computers it's a horrible risk (since PC value drops like a rock). It also says something about poor financial planning when you must finance luxuries (rather than necessities, which includes the car and the house).
Overall, it's a very risky action for a luxury good. Save for a few months and get it in cash - and pay less money too.(*)
(*) All that being said, if your financial situation is strong, you have your 401(k) fully funded every month, you have $100,000 in the bank in spare rainy-day cash, and you don't need to worry about income, and you're doing this simply for the reason you described and have no other need for the money aside from a better time-value usage of it, go for it. But most people can't honestly say that or anything like that.