Usually they come with Works like every other Dell. You can't get them with Office. If the description says XP or Vista that what it comes with. They also come with a 1yrs warranty which is better than the 90day offered by the cheaper models on the main Dell site.
I've bought a few, found it a great way to buy. Like all Dells, or mass produced machines you get the odd one with a fault, but I've had no problems with returns on the outlet.
The ebay outlet can be cheaper but I've never managed to outbid the snipers, and the price usually goes up in the auction making it less a Deal.