I buy a lot of computers from Dell (and others) for clients, and I also build a lot of PCs too. All of my personal computers (except the notebook, which is a Lenovo) are handbuilt by myself, and have been since the mid 90's.
About pricing:
If your price point is about $600 or less, and especially if you need a new monitor, then a Dell is pretty much always cheaper option. This is especially true if you aren't too fussy about specific components or the specs of the monitor. If you wait for the deal-de-jour, then shipping can be had for free too.
If your price point is between $650 and about $1100, then it is definitely cheaper to build it yourself, provided the time spent building it is "free to you." I just built up a new system for myself that ran about $800 in parts, where an equivalent system from Dell priced out at $1200. The one I built up has the best-of-breed for every component type (Corsair memory, Seagate Hard Drive, LG Blu-Ray Burner, Silverstone Case, Asus motherboard, etc.) and comes in a form factor I prefer (an utterly silent shoebox-style SFF case), whereas the Dal uses whatever components they got deals on for this fiscal quarter in a standard mini-tower. If you have to pay a consultant to build it, however, the pricing starts to fall in line with what Dell offers.
If your price point is greater than $1200 or so, then it is always cheaper to build yourself, or even have a computer guy build it and you pay him for his time. Sometimes the cost difference is two or three times.
About Warranties from Dell:
Unless you have the warranty where a Dell technician physically drives over to your house and fixes/replaces bad components on the spot (and these aren't cheap), then it is generally still up to you to diagnose the problem (phone support is very hit-or-miss here), and then turn the screwdriver yourself to replace the bad component when the replacement arrives. Lather-rinse-and-repeat if the problem is complex and involves multiple components.
In the end, my clients find it less aggravating to have me come over, diagnose the problem, come back with a replacement part from Newegg or Fry's, fix it, and then pay me my hourly rate, along with the cost of the new part. Don't forget that having a receptionist wait on the phone with dell and try to diagnose it, and then waiting for the replacement part to get shipped costs the company money in lost time and productivity. It's cheaper to get me to do it outside of the warranty overall.
So, if your time is free to you, and you don't get aggravated easily, then the Dell warranty is perfectly fine, I guess, but you'll still be doing most of the work to fix it. You might as well built it yourself since you're responsible for fixing the dell anyways...
My two cents,
Llama
