Best policy is to get a barebones system from the likes of Scan, Aria, Overclockers etc or to just call them up and ask for a decent system.
Off-the-shelf PCs seem to (ime which is admittedly not that current) chuck in dodgy cheap stuff when you’re not looking, and they install for you a shitload of stupid software on top of windows that does nothing but go wrong and clog your machine up.
If you get a machine from one of those companies, it’ll be made from named components and come with a plain Windows installation and probably the actual Windows CD, which is useful.
You’d be amazed how quick a plain Windows installation can be.
Also, remember the very latest processors will be far more power than you need unless you are gaming or 3D rendering or something. The shop should be able to advise you on the best value for money.