I had 2 dell pcs consequitively (both different), and both developed problems and needed replacing after 28 months. Strangely, the eact same thing has happened to several of my friends at about the same period after purchase..At that age technology has imporved and prices gone down, that its cheaper to replace outright than faff with repairs. Strange that.
I decided to go eslewhere, and after HOURS of research as to reliable companies, had one custome built to my exact spec by www.pcspecialist.co.uk
Better spec and exactly what i wanted and vastly cheaper than i could get the stuff i wanted at Dell or other places and lasted 4 years without problems (and then just needed new hard drive).Would recommend a look at least.
Having said that, If you want something relatively good value, and dont mind replacing it more often, Dells are fine.