There were some very attractive deals in PC World recently, I bought a top of the range HP for less than �500 just after Christmas. Definitely worth a look. But don't get sucked into their free laptop deal, you have to sign up for something that ends up costing more than the laptop anyway.
I recommend you to have a look at the November 2008 issue of Which Computing Magazine. It compares 12 laptops having tested them for all key aspects such as comfort, how well the keyboard performs and the quality of the screen. For each one they give the dimensions, weight ,screen size,processor, memory, hard drive, webcam, battery life ease of use, versatillity etc. It also gives marks for each one.
You may be able to see a copy at your local library.