Hi,
In general, for your own use, I'd say build.
If you're looking for the best price, copy the specs from the Dell machine you are considering, go to
newegg and/or
pricewatch and look for the total cost of all the equivalent components. Be sure to compare apples to apples as much as possible (i.e., go for the cheapest no-brand items or at best OEM versions of branded items -- that being basically what Dell uses). I've usually found that, by selecting from multiple vendors and watching the shipping and tax costs, I can beat Dell's price and build just as crappy a machine.
Now, if you actually want a machine for more than e-mail and porn downloading, you'll probably find that the basic Dell will not cut it. To build a machine for gaming, graphics or video processing, or program development, the upgrades to the Dell machine will often cost more than the products that are used for the upgrade. Again, these upgrades will typically be the cheapest available or stripped down OEM versions. That is assuming you can even get the capabilities you want from Dell in the first place. So, you'll either have to pay much more, or settle for something that isn't quite right.
I'd suggest figuring out what you really want to do, then spec'ing a complete list of components that you are considering will do the job to these forums. You'll get some good advice as to whether what you've picked will play well together and do what you want to do. Follow the advice in the links for building your own computer when you do get the parts. And post problems here.
As to how long it takes to assemble a system, that depends on experience and how much hardware/software tweaking you want to do. The twenty minute figures are probably valid for basic assembly. It takes me longer than that to strip the case down, figure out all the cooling and cable pass through holes, other case mods I want to make (such as relocating drive bays for better cooling), mark them, cut them, and clean and reassemble the case. But then, I'm anal
For a first time builder, it'll take a few hours just to read through the online guides, the manuals shipped with the products, and to get all that info correlated in your head. If you skip the reading and screw up and fry a part, those few hours will be cheap relative to the time it takes to get an RMA, ship the 'defective' part, get a replacement, etc.
If you take your time, check on the net and here on things you are unsure about (such as BIOS setting and XP components), then a more realistic first time build time would probably be one long day, or even two, from opening the first box to a complete XP boot, all devices recognized.
Of course, you could just go hell bent for leather, throw the system together in '20 minutes' and then spend weeks working all the glitches out. Just look at all the "I just finished building a new system and xxx doesn't work, HELP" posts
😉
--Pete