There are very few things I will buy extended warrenties on, but with computers and my daughter's very expensive camera's I do. Can't tell you how much money I've saved by doing this.
Having said that, I'm so sorry you're having so much trouble with your computer. I just found out that when you use certain credit cards, they offer an extra year on warrenties on certain items at no extra charge. It's just a plus they offer. It might be worth looking into it with your credit card company, assuming you paid by cc. Good luck!