Dont go for dell, they arent that great, i work with them day in day out and i cant stand the fuckers, your best bet is to get one built, if your local give a guy brian at pc medic a bell (01793 433300)
www.pcmedic.co.uk i think or .com.
His shop is by the wssmith warehouse just off greenbridge.
Pop in and see him, tell him what you want and he will sort it out for ya he's very well priced aswell.