Search the last few pages of the consumerwatch and you'll find there have been several discussions on this over the last few weeks.
If weight isn't a problem then you've got a massive market. PC World have some good deals so that may be a good starting point.
Technoworld click here are one of the best suppliers I've had dealings with so have a look around their site.
Laptops tend to be built by a few companies and rebadged by the rest so there often isn't much to choose from.
My suggestion is have a look yourself and see what you/your dad likes and then post back with a shortlist of about 5.