I'm not a great fan of extended warranties - I remember my parents bought a midi stereo system about 10 years ago - it was expensive.
They were convinced to get the 5 year extended warranty - it cost nearly 50% more than the actual product itself!
As it turned out, the stereo system was an Aiwa which had intractable problems with the CD player - it was repaired about 6 times over 5 years. Each time it didn't really make a lot of difference. In the end I fixed it myself, by adjusting a couple of pots on the laser module. Since then it's been fine for 5 years.
Being in the UK however, I think I'm quite lucky. Retail law in the UK is quite strong. If for example, I bought a £400 DVD-recorder and it breaks 1 month after the manufacturer's 90 day warranty expires, I can go back to the shop and ask for a repair/replacement. As long as I could argue that it would be reasonable to expect a £400 DVD-recorder to last more than 4 months without breakdown, then the retailer is legally obliged to repair/replace at their cost.
Of course, few consumers know this - so retailers continue to sell warranty protection, to customers who already have this proteection under law.