Like many other folks, I make big ticket purchases on store credit (or in the case of Apple, Barclays) and use the no interest period of time to pay it all the way off. If a retailer like Best Buy goes belly up, I'm pretty sure that whomever takes over can do whatever they like with the financing.
Also, in many cases if you get a dud unit, the manufacturer will tell you to go to the retailer first.
I know it is all far fetched, but seeing Compusa go down was crazy. That store was always packed. Likewise for Circuit City. It was kind of the "Sears" to Best Buys "Target", but I always visited both when I was making a purchase to see who had the better deal.