The only good thing about Dell is they are the cheapest on the market so they will suit your budget BAHCO, personaly though if you can afford it, avoid them. For starters they advertise their products with a TFT screen but in the specs its an analouge monitor
I live by the HP Pavillion brands (Im on my third) and would not buy any other. You wont get one for £400 though, but you get what you pay for in life.
It sounds as though you require a low spec machine for simple,mundane tasks. I would insist on a dual layer dvd/cd recorder as the dvd's are excellent for backing up all your mp3's & data files. Good luck with whatever you decide