I would have to disagree with all of the above.
I've been happily running Dell machines as servers, clients, laptops - you name it for 7 + years.
On the odd occasion I have experienced a problem I have always found both their online support (using the Service tag) and telephone support well above satisfactory. I find that their combination of parts is very reliable and easily upgradeable.
As Richard and newswatcher have stated, you will always find someone with a horror story from any supplier.