No need whatsoever to pay somebody your hard-earned money to set the PC up for you. First, use a 12 year old nephew if you have one. Failing that do it yourself ! As someone has already said, all the plugs and sockets will be colour-coded and the OS will be pre-installed. You might have to match your printer to your new desk-top but that is normally easy-peasy.
If you just need the tower unit, then you should have no problem in finding something really good value. Pop along to your nearest PC World and have a ganders.
As regards drivers, its likely that you will only need them for your printer, and the printer should self-install, as long as it was purchased relatively recently, ie in the last 10 years. Monitor and keyboard are just plug and go...same with mouse.
Please don't pay anyone ( apart from nephew ) !