I can really comment on a laptop as i have never had one, always prefered desktops, however i can reccommend a company to purchase a desktop from. have a look on click here. I was a bit like you, needed a new computer but didnt really know what i was looking for. They have plenty of systems to choose from, but i rang up and spoke to their sales department. They actually advised me on a cheaper system to the one i was originally looking at which just shows they will sell you a system to suit the customer not just try and sell the more expensive computers.
Its worth a call just to get some advice on what processor, motherboard etc to use.