From the letters I’ve gotten re: Sony’s repairs, the extended warranty may be good thing if the store will let you swap it and your alternative is to send it back to Sony for repair.
For me, it depends on the item and how much the warranty costs vs. the cost of a typical repair. On a stereo, for instance, I wouldn’t get one on the receiver (almost no moving parts), but I might consider it on a CD or DVD player. I did get one on my Sony WEGA, due to the short labor warranty and the cost of the item (and the reasonable price of the warranty). Of course, buying the warranty meant my first three years were trouble-free. :)
If a product is under $150 or so, I’d definitely not bother with an extended warranty. Dead electronics = “ooh, I can upgrade!”
For stuff like video cards, chances are that failure is going to occur (1) when the product is still fairly new and under warranty, or (2) when it has a couple of years of heating/cooling behind it and you’d be happy for an excuse to upgrade anyway. (Or you can buy an identical used card for $30 on eBay…)
In fact, that’s probably not a bad rule of thumb on the extended warranty – how much is the extended warranty vs. what the product will sell for on eBay in two years? If the warranty is more than 1/4 of the cost of an eBay replacment, play the odds and skip it.
Say somebody buys a refrigerator, dishwasher, TV set, DVD player, speaker system, MP3 player, and video card from Circuit City or Best Buy over the course of a couple of years, and buys warranties for everything. Chances are, for the cost of the warranties, you could replace any of the items with a new item for the same amount of money. And if nothing dies, you have enough extra cash to buy a new toy. What are the odds of more than one of the items going belly up?
Also, when my Sony 5-disc DVD player fritzed out about a year ago, the repair was $60 – less than the warranty would have cost.
The one place I’ve seen these pay off is when you can get credit towards a new item instead of an exact replacement. Sony only manufactures Clie handhelds for about 6 months before coming out with new models – I’ve had readers report replacing dead Clies at Best Buy with dramatically better models at no cost. (Well, other than the warranty cost.) Same thing with cell phones.