I swear by Dell refurbs. You have to watch the model and the timing though, because depending on the model you sometimes get as good a deal on new units with coupons; this is especially true of the consumer lines (Dimension, Inspriron, XPS). Also it really depends on the configuration.
On the other hand, with the business lines (Optiplex, Latitude, Precision) is where you can make out like a bandit. You can save some serious coin, *AND* you get the 3-year warranty standard.
From the Outlet I've bought the following over the years:
Dimension 3500 desktop. Several years ago, looked brand new; since sold.
5100cn color laser printer. This thing is a BEAST. 85 pounds, built-in duplexer (2-sided printing), 12-13 pages per minute in color, 25 pages per minute in black. Hands down beats the HP pieces of crap we have here at work. At the time it was a phenomenal deal, roughly half the cost of a new one (paid a little over $400, new price was about $900). When I got it the page counter showed that fewer than 200 pages had been printed on the unit. Still going strong. Love the damned thing.
Latitude E6400. Bought a month ago with a 15% coupon. P8600, 2GB RAM, 9-cell battery, backlit keyboard, 160GB hard drive, 1440x900 LED screen. After tax it ended up at $695 shipped, which is about half price. Again, looks brand spanking new. Since this model is brand new (only been out since September), now is the perfect time to buy one, since the unit can be at most 4 months old. No chance it's been languishing in inventory or was used heavily prior to your acquiring it. P.S. I dropped in a 4GB RAM kit and replaced the HD with an SSD and this machine is speedier than any desktop I have at work. Great screen, light, and 6-8 hour battery life. SexyBeast.
XPS 630i. Just received 3 days ago. Q9550 CPU (2.83 Ghz, 12MB cache), 4GB RAM, 750GB hard drive, Vista Home Premium 64-bit, dual Radeon 4850 Crossfire. $1,100 shipped. I was looking to upgrade from my XPS 410 and am doing some things with SSDs, but didn't want to take the time to research and build an entire new unit from scratch, so this seemed like a good route. When I inquired on another board about a system build with similar specs, it was only going to be $50-100 cheaper, and I don't have to mess with the core build. Good starting point to then swap in components and tweak. The case itself is sleek and very well put together. Dell's getting better on the usability of their cases at the high end. System is very speedy, although I haven't done any tweaking yet. Put in an 8GB RAM kit from Newegg and last night replaced the 750 GB drive with a pair of Intel X25-M SSDs in RAID 0. Power off to desktop fully booted in under 30 seconds (and that includes 4-5 seconds pause at the RAID manager in case you want to enter). 750GB drive will become my data drive.
Enough blathering on my part. At any rate, I have never had any problem with units from the Dell Outlet. Same warranty as new systems and a 21-day return privilege. How can you go wrong?