Before I talk about the mentioned above I have found a great laptop at PC World. click here=
This is not an own brand laptop. This is made by Compaq that is a subsidiary of HP. Do not purchase an own brand laptop from PC World e.g. Advent, Packard Bell, Philips or you will run into heaps of problems in the future. I am sure the laptop I have picked will fulfill all your needs
The dells are a bit weird because you can tailor them to your needs or chose a pre built system.So I cannot advise you as they come with a very wide range of specifications. The dell laptops do get good reviews but be wary of their technical support dept.
Sony laptops are of excellent quality and come with good support but be beware of the high price tag.
I also recommend paying Novatech a visit click here or PC Specialist click here
So out of your three I pick the sony but I highly reccomend the Compaq from PC World