How long is your warranty on it currently? I opted for a 3 year warranty and it's more than regained the price. I think I paid $99 for the warranty.
After I year, I've replaced my screen once, my hard drive once, my dvd drive 3 times. If I didn't have my warranty, it woulda cost like $500 just for the screen alone.
Dell computers are notorious for needing replacements/repairs, at least in my experience.
I always opt for the warranty on a laptop if it's a pricey model. Pretty much everything else I dont get the extended warranty.
edit: A few of my friends who opted for 3-4 year warranties on their laptops got newer models when the old model wasn't supported. A friend who had her mobo die on her 8000 inspiron got a 8500 as a replacement because they no longer supported the 8000. Ditto on my Inspiron 8200. If the motherboard ever dies on this one while I'm still under warranty, they'd replace it with a 8500.