I work with Dells all day (corporate laptop technician) and the problem with Dell isint their propritary parts, its their lack of QC, horrible product design, and willingness to cut costs..
Any time I run a diagnostics on a laptop, usually there is a hard drive problen, what hard drive is in it? A fujitsu or Hitachi, sometimes a WD. Ram is from random companies, whoever will give them the lowest bulk price, Ive never heard of any of the ones Ive seen execpt for Infinion. My personal favorite, is that the processors have no thermal paste between them and hte heatsink/fan combo. Your lucky is they have thermal tape. The design flaws are enormous, from how the chassis are made, to the mounting of the display, etc. They wonder why they break so much. Instead of being designed with a mindet of whatws teh best way to make this soit wont break, and if it doesnwhats the most efficient way to fix it, its how can we make this as cheap as possible. The customer support is widely known for being sub par. We also have all seen the ammount of quality control (QC) that they lack. Here are a few links that might help to go along with the one that zdude posted:
http://dailytech.com/article.aspx?newsid=3328
http://www.npr.org/templates/story/story.php?storyId=5532228
(click listen on the second one)
Maybe their Desktops are constucted a bit better, but overall, I wouldnt get them. The only time I reccommended one was for my sister, becuase she needed somethign cheap, (shoudl have went to ibuypower, but I didnt think about it) and I knew that she was going to take very good care of it so it woulld have a better chance of staying together for a while. Also , I can fix them if she needs it.