I just bought an XPS through my University Program. Actually came to a pretty good deal. If you're using it for gaming, you'll definitely need to upgrade the card.
I got the 730x with
i7 920 @ 2.66 ghz
6 gb ddr3
GTX 280 1024 MB
WD Velociraptor 300 GB HD
Soundblast X-Fi Titanium Sound Card
For around $2,400, which isnt too bad as opposed to building something through Memory Express or NewEgg.
I've had great experiences with XPS systems, especially the top models; they tend to be built well and are fully upgradeable. Everything in the 730x you can upgrade, uncluding the mobo. I plan on purchasing an additional GTX 280 to run in SLI, as well as purchase an additional HD for cheap, to store movies and music on, as the Velociraptor drive is going to run OS and applications only.
EDIT: Here is a link to a guy that reviewed it. I did a fair bit of research before, and his review leaves him pretty satisfied
http://www.hardforum.com/showthread.php?p=1033677886