I don't think I've heard your story, but if you've had to use their service a few times, doesn't that mean they keep breaking?
Yep, you'd think that. But i'd say the risk of your notebook breaking down at least once in the time you have it is generally pretty high... especially if you carry it around everywhere in your backpack, accidentally drop it once or twice and generally don't handle with extreme care (Dell please don't read this

). My notebook travels a lot and it's a 17" so it's a little heavier on the bumps. They have much the same components as other laptops (HDD's etc) so I don't see the risk being any greater.
I've probably been on the more extreme side with almost the whole notebook being replaced (HDD, Screen, Mobo (for the graphics card), keyboard), but I think my point is, i'd rather not have to send it away for two weeks if something went wrong.
My gf's studio hasn't had any issues yet, but I know of a few other dells that have had mobo's replaced due to a graphics card issue. The support is usually a painless process. Phone, tech comes out with new part the next day (usually early morning), leaves in 20min, I carry on working. Across the whole office, happened about 4 times last year, every time we lost at most 18 hrs downtime (over night + a few hrs extra).