I bought an XPS desktop and a 19" LCD monitor from Dell about a year ago and have not had a single problem. It is the most stable system I've ever had and would highly recommend them. My buddy also has had a Pentium4-based XPS for over two years and no problems. I like the case designs for their cooling, compartmentalization, and ease of future upgrades.
If you do buy a new system check to see what specials they have going on. I got 0% financing for 18 months and also saved about $200-$300 in upgrades, plus the top of the line monitor upgrade was only $50.
