If buying cheap computers maybe and you only have 1. I do complete rebuilds on mine usually in the area of once a year and in most cases it's a fraction of the cost, many times I actually get a better system than simply replacing. A cpu gain from 2.4 ghz to 2.8 ghz afterall isn't that big of a jump if you don't also upgrade the rest of the system, of which I do
Don't let anyone talk you in to getting an Alienware because they make gaming PCs. Visit alienwaresucks.info to hear my gruesome tale. $4,000 down the drain. Get an Apple. Nothing fancy or expensive? Christmas is coming. Wait until all the computer deals come out then get a new one. Dell.