The reason why it's that cheap...
- Dell gets volume discounts on everything. Including the OS which is like $10-$20 a license to them versus $100 a license for us.
- The GPU is nowhere near fitting for a "extreme performance system" that XPS stands for. It's a HD7570, that's worse than a $100 card.
- They more than likely skimp on everything else.
Also I don't understand your question, but I'm going to assume you meant "what" instead of "why", but you should be able to do the same thing to a Dell as you would a regular desktop computer now and days.