If you are computer savvy and are capable of doing an OS install, then you can decide whether to build your own system or not. Realize that as the previous poster said you can save 800.00, is not even close to true. At todays prices, you would be hard pressed to build a system with the same specs for what you can buy retail for.
Yes you can get the cheapest of components, but when they don't work then who are you going to call?
I have built systems for years, but stopped doing any except my own. Off the shelf has a warranty, tech support and you can just return it if it doesn't work to start with.
Compaq - HP - DELL - Gateway Everyone has a good story and tales of disaster to tell about each.
If your going DELL, buy from the business division and get GOLD tech support.
Off the shelp I have sold many Compaq and HP units. Once in awhile they have the same problems you would if you built your own, such as hard drive failures, mainboard failures, bad DVD drives, etc.
If you are willing to be your own troubleshooter and return parts to the manufacturer of the parts for replacement, then build your own, but I recommend not doing that if you're not pretty well up on how to do it.
Grammar quite often can tell you about the person giving you information. When I read the prior post, it gave a wealth of information about that person's abilities.