I had a dell 2 years ago, before i took the plunge and did a build it myself PC buying all the parts from OCUK mainly
Differance in quality & performance is night and day, and funnily enough it did not cost a huge amount more than i paid for my dell (£200.00 more for the system)
My Dell did not have a seal on the back, however i bought it from there outlet (returned PC's) so got it a bit cheaper, the HD failed exactly 1 year after i bought it, no surprises who had to pay for a replacement....
There famed helpful tech support went down the toilet the second they outsourced it to India (The only decent thing they had going for them), nothing against Indians, but the way these call centres are run, they have them lined up like robots and they literally read all there answers from a script resulting in zero help for anything that does not fall into problem A, you answer with responce B, ask an off script question and the poor buggers dont know what to do
Tip for the future dont buy Dell again, or any other brand make for that matter, build you own, or buy a pre built system that use's decent non proprietry parts, like system from OCUK