Does Dell sell Lemons?

I have a Dell Inspiron 9400 which Dell has just returned as it is 2 months past warranty and the Motherboard has fried. More than $500 to fix.
My question is whether anyone has had the same issue with Dell? Is there a significant number, enough to justify advising people not to buy Dell products as either they produce a large number of lemons or refuse to back their products. (customer sevice)

Just want to see if its just mine thats a lemon.